Error with simple UILabel?

I have a little problem:

I have a view with a view controller and a tabbarcontroller in a main window.

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:     (NSDictionary *)launchOptions
{
// Override point for customization after application launch.
// Add the tab bar controller's current view as a subview of the window

self.window.rootViewController = self.tabBarController;
[self.window makeKeyAndVisible];

On this view I have around 10 Labels.

As soon as I connect 1 Label on the Interface-Builder with the UILabel in the controller, I get a SIGBART error.

Here is my code:

#import <UIK开发者_运维百科it/UIKit.h>

@interface SelfViewController : UIViewController
{
    IBOutlet UILabel *id2;
    IBOutlet UILabel *username;
    IBOutlet UILabel *vorname;
    IBOutlet UILabel *nachname;
    IBOutlet UILabel *email;
}

@end

What am I doing wrong?

Here is a solution, very basic and simple but very frustrating too: https://discussions.apple.com/thread/1598422?threadID=1598422