Thanks for your help @WhiteYoshiEgg !
I tried applying everything you said, but my problem was still there.
After loading the 'Nintendo Presents' Logo, the screen went black and the game crashed.
I tried, doing some other stuff, but nothing worked. In the end I tried doing the same with uberASM and everything went fine!
My theory is: The game is writing the 'Mario' every Frame to the status bar, even when the status bar isn't displayed and is used for other code.
I'm pretty glad, that stuff worked in uberASM ;)
But anyways: Thank you so much for your help! I really appreciate it!
I don't know, what I should put here.