Help! When i add my main menu to the build settings, and build the game, it crashes

Can anyone help me please! I have made my main menu and did the scripting in java and when im done and tested if the buttons work or not and i saw that they work. So when i try to build the game i add my main menu and My level and i click build the game.

When i click play it load the unity splash screen and crashes giving me crash reports.

Also when i Delete the Main Menu from the build settings and leave my leavel on there and build the game, it works just fine. Please someone tell me why is this happening!! Please