Hi, I need help desperately. I keep getting the following error: 2008-12-29 21:28:23.609 TabApplication[7510:20b] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[UIViewController printSomething]: unrecognized selector sent to instance 0x529c80' I basically created a UIButton and connected an action to it -- nothing too fancy. But I keep getting this error. I think it has something to do with the UITabBarController. Everything works well on the MainWindow.xib, but this error is generated on another .xib file which is loaded by the second UITabItem. I used the built-in Tab Bar application when I created the project. Any suggestions? Please. I lost two days on this error. Thanks. Roei.