App Crashes if Menu-Button gets activated

I programmed a basic app interface and it runs alright on the nougat emulator APIv25. But if I press the right button of the menu bar at the bottom of the emulator the app crashes. The "back-button" and the middle "menu-button" of the menu bar work perfectly. Can someone help me and tell me what's the problem?

Thanks a lot for your replies.

Sign In or Register to comment.