loading mutliple nib files

Hey guys, I know this is kind of a noobie question, but I have a View Controller that loads a nib file, but I want it to also load another one when a button is pressed. I have this:

Code:

[NSBundle loadNibNamed:@"Chart" owner:self];

In the action for my button but I get a warning and when the button is pressed the program crashes. Is that the right line of code?

Thanks