iOS UIButton action no more working in Xcode 3.1

#import <UIKit/UIKit.h>

@interface LottoGeneratorAppDelegate : NSObject <UITextFieldDelegate> {
    UIWindow    *window;
    UIImageView *contentView;
    UILabel     *label;
}

@property (nonatomic, retain) UIWindow *window;
@property (nonatomic, retain) UIImageView *contentView;
@property (nonatomic, retain) UILabel *label;

@end

#import "LottoGeneratorAppDelegate.h"

#define BUTTON_FONT_SIZE 14.0
#define TEXT_LABEL_FONT_SIZE 12.0
#define MARGIN_TOP 110
#define MARGIN_LEFT 104
#define LABEL_BG_ALPHA 0.2

@implementation LottoGeneratorAppDelegate

//Generates accessor methods
@synthesize window;
@synthesize contentView;
@synthesize label;

//Declare a array with pointers to UILabel
NSMutableArray *mylabels;
NSMutableArray *mystarlabels;

- (void)addControlsToContentView:(UIImageView *) aContentView {  
	//Allocate memory for mylabels array
	mylabels = [[NSMutableArray alloc] init];	
	mystarlabels = [[NSMutableArray alloc] init];	
	
	//CGRect contentFrame = aContentView.frame;
	
    // Create a button using an image as the background.
    // Use the desired background image's size as the button's size
    UIImage *buttonBackground = [UIImage imageNamed:@"Button.png"];
    CGRect buttonFrame = CGRectMake(0.0, 0.0, buttonBackground.size.width, buttonBackground.size.height);
	UIButton *button = [[UIButton alloc] initWithFrame:buttonFrame];

    [button setTitle:@"Generate" forState:UIControlStateNormal];	
	button.font = [UIFont boldSystemFontOfSize:BUTTON_FONT_SIZE];

    // Center the text on the button, considering the button's shadow
    button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;
    button.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
    button.titleEdgeInsets = UIEdgeInsetsMake(-2.0, 0.0, 2.0, 0.0);   //Create inset for the shadow below
    
    // Set the background image on the button
    [button setBackgroundImage:buttonBackground forState:UIControlStateNormal];
	[buttonBackground release];
    [button addTarget:self action:@selector(generate:) forControlEvents:UIControlEventTouchUpInside];  //generate: is sent when the button is touched
    
    // Position the button centered horizontally in the contentView
    button.center = CGPointMake(aContentView.center.x, aContentView.center.y+175);
    [aContentView addSubview:button];
    [button release];
	

	CGFloat posx = MARGIN_LEFT;
	CGFloat posy = MARGIN_TOP;
	CGRect labelFrame;
	UILabel *aLabel;
    // Create labels for Numbers
	int i;
	for(i=1;i<=50;i++){
		posx += 23;
		if((i % 5)==1){
			posx = MARGIN_LEFT;
			posy += 18;
		}
		labelFrame = CGRectMake(posx, posy, 22, TEXT_LABEL_FONT_SIZE +5 );
		aLabel = [[UILabel alloc] initWithFrame:labelFrame];
		aLabel.font = [UIFont systemFontOfSize:TEXT_LABEL_FONT_SIZE];
		aLabel.textColor = [UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:1.0];
		aLabel.backgroundColor = [UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:LABEL_BG_ALPHA];
		aLabel.textAlignment = UITextAlignmentCenter;
		aLabel.text = [NSString stringWithFormat: @"%d", i];
		//Register label in array
		[mylabels addObject: aLabel];
		self.label = aLabel;
		[aLabel release];
		[aContentView addSubview: self.label];
	}
	posy += 1;
	
	for(i=1;i<=9;i++){
		posx += 38;
		if((i % 3)==1){
			posx = MARGIN_LEFT;
			posy += 24;
		}
		
		///place the stars
		CGRect starFrame = CGRectMake(posx+6, posy, 25, 23);
		UIImageView *anImageView = [[UIImageView alloc] initWithFrame:starFrame];
		anImageView.image = [UIImage imageNamed:@"star.png"];
		self.contentView = anImageView;
		[anImageView release];
		[aContentView addSubview: self.contentView];
		 
		
		//Place the Labels
		labelFrame = CGRectMake(posx, posy, 37, TEXT_LABEL_FONT_SIZE +12 );
		aLabel = [[UILabel alloc] initWithFrame:labelFrame];
		aLabel.font = [UIFont systemFontOfSize:TEXT_LABEL_FONT_SIZE];
		aLabel.textColor = [UIColor colorWithRed:0.5 green:0.5 blue:0.5 alpha:1.0];
		aLabel.backgroundColor = [UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:0.0];
		aLabel.textAlignment = UITextAlignmentCenter;
		aLabel.text = [NSString stringWithFormat: @"%d", i];
		//Register label in array
		[mystarlabels addObject: aLabel];
		self.label = aLabel;
		[aLabel release];
		[aContentView addSubview: self.label];
	}
}

// This method is invoked when the generate button or return key is touched
- (void)generate:(id)sender {
	NSLog(@"Lotto numbers generated.");
	NSMutableArray *zufallsArrayNumbers;
	NSMutableArray *zufallsArrayStars;
    zufallsArrayNumbers = [[NSMutableArray alloc] init];
    zufallsArrayStars = [[NSMutableArray alloc] init];
    NSNumber *zufallszahlNumbers;
    NSNumber *zufallszahlStars;
	//Shuffles Randomizer
	srandom(time(NULL));
	
	//Variables for for-loops
    int a,x,i;
    BOOL valid;
    for (a = 0; a < 6; a++){
        valid = false;
        // Solange Zufallszahlen erzeugen bis eine gültige, noch nicht
        // vorhandene Zahl ermittelt wurde.
        while (valid == false){
            // Neue Zufallszahl erzeugen
            zufallszahlNumbers = [[NSNumber alloc] initWithInt:(random() % 50)];
            // Diese Zufallszahl ist einmalig bist das Gegenteil bewiesen ist
            valid = true;
			
            // Prüfen ob diese Zahl mit einem Elemente
            // im Array übereinstimmt
            for (x = 0; x < [zufallsArrayNumbers count]; x++){
                if (zufallszahlNumbers == [zufallsArrayNumbers objectAtIndex:x]){
                    // Übereinstimmung gefunden,diese Zahl gibt es schon
                    valid = false;
                    // Zahl aus dem Speicher entfernen
                    [zufallszahlNumbers release];
                    break;
                }
            }
        }
		
        // Neue Zahl ermittelt. Zahl zum Array hinzufügen
        [zufallsArrayNumbers addObject: zufallszahlNumbers];
        [zufallszahlNumbers release];
    } 
	
	for (a = 0; a < 2; a++){
        valid = false;
        // Solange Zufallszahlen erzeugen bis eine gültige, noch nicht
        // vorhandene Zahl ermittelt wurde.
        while (valid == false){
            // Neue Zufallszahl erzeugen
            zufallszahlStars = [[NSNumber alloc] initWithInt:(random() % 9)];
            // Diese Zufallszahl ist einmalig bist das Gegenteil bewiesen ist
            valid = true;
			
            // Prüfen ob diese Zahl mit einem Elemente
            // im Array übereinstimmt
            for (x = 0; x < [zufallsArrayStars count]; x++){
                if (zufallszahlStars == [zufallsArrayStars objectAtIndex:x]){
                    // Übereinstimmung gefunden,diese Zahl gibt es schon
                    valid = false;
                    // Zahl aus dem Speicher entfernen
                    [zufallszahlStars release];
                    break;
                }
            }
        }
		
        // Neue Zahl ermittelt. Zahl zum Array hinzufügen
        [zufallsArrayStars addObject: zufallszahlStars];
        [zufallszahlStars release];
    } 
	UILabel *tmp;
	//clean the labels
	for(i=0;i<[mylabels count];i++){
		tmp = [mylabels objectAtIndex:i];
		//tmp.textColor = [UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:1.0];
		//tmp.font = [UIFont systemFontOfSize:12.00];
		tmp.backgroundColor = [UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:LABEL_BG_ALPHA];		
	}
	//clean the starlabels
	for(i=0;i<[mystarlabels count];i++){
		tmp = [mystarlabels objectAtIndex:i];
		tmp.textColor = [UIColor colorWithRed:0.5 green:0.5 blue:0.5 alpha:1.0];
		tmp.font = [UIFont systemFontOfSize:12.00];
		
	}
	//Set 6 random labels // O(1)
	for(i=0;i<[zufallsArrayNumbers count];i++){
		tmp = [mylabels objectAtIndex:[[zufallsArrayNumbers objectAtIndex:i] intValue]];
		//tmp.textColor = [UIColor redColor];
		//tmp.font = [UIFont boldSystemFontOfSize:12.00];
		tmp.backgroundColor = [UIColor colorWithRed:1.0 green:0.3 blue:0.3 alpha:0.6];
	}
	//Set 2 random starlabels // O(1)
	for(i=0;i<[zufallsArrayStars count];i++){
		tmp = [mystarlabels objectAtIndex:[[zufallsArrayStars objectAtIndex:i] intValue]];
		tmp.textColor = [UIColor colorWithRed:1.0 green:0.0 blue:0.0 alpha:1.0];
		tmp.font = [UIFont boldSystemFontOfSize:12.00];
	}
	//Reset pointer
	tmp = nil;
	[zufallsArrayStars release];
	[zufallsArrayNumbers release];
}

- (void)dealloc {
    [contentView release];
    [window release];
    [label release];

	[mylabels release];
	[mystarlabels release];
    [super dealloc];
}

#pragma mark -
#pragma mark UIApplication delegate method

- (void)applicationDidFinishLaunching:(UIApplication *)application {
	[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleBlackOpaque];
    // Set up the window and content view
    CGRect screenRect = [[UIScreen mainScreen] bounds];	
	UIWindow *aWindow = [[UIWindow alloc] initWithFrame:screenRect];
	self.window = aWindow;
	[aWindow release];
      
    // Add the image as the background view
    UIImageView *anImageView = [[UIImageView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]];
    anImageView.image = [UIImage imageNamed:@"Background.png"];
    self.contentView = anImageView;
    [anImageView release];
    [window addSubview: self.contentView];
    [self addControlsToContentView: self.contentView];
    
    // Show the window
    [window makeKeyAndVisible];
	//Generate numbers
	[self generate: self.contentView];
	NSLog(@"Lotto generator started.");
}

@end