Saving Changes to Managed Objects

I'm trying to edit a property on a managed object, but for some reason the changes aren't being saved. I'm using the following code:

Code:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (indexPath.section == 3) {
        
        NSManagedObjectContext *context = [[self appDelegate] managedObjectContext];
        
        NSNumber *num = [self.word valueForKey:@"active"]; // "word" is a managed object
        
        if ([num isEqualToNumber:[NSNumber numberWithInt:1]]) {
            num = [NSNumber numberWithInt:0];
        } else {
            num = [NSNumber numberWithInt:1];
        }
        
        [self.delegate wordWillBecomeInactive:self.word]; // Just a little protocol I wrote
        [self.word setValue:num forKey:@"active"];
        
        NSLog(@"%i", [context hasChanges]); // Prints 0
        NSLog(@"%@", [self.word changedValues]); // Prints an empty dictionary
        
        NSError *error = nil;
        [context save:&error];
        
        [self.tableView reloadData];
        
    }
        
}

If I NSLog the value "active" then it shows up as being toggled, but it doesn't save. Anybody know what's happening?

 

Error

I NSLoged the error, and it was (null).