@mirko Hi! Please supply this info so we can help you better:

Pi Model or other hardware: (B, B+, 2 B, 3, X86 PC etc..)
Power Supply used: (If using a Pi)
RetroPie Version Used (eg 3.6, 3.8.1, 4.1 - do not write latest):
Built From: (Pre made SD Image on RetroPie website, Berryboot, or on top of existing OS etc.. - please provide the filename of any image used)
USB Devices connected:
Controller used:
Error messages received:
Log found in /dev/shm/runcommand.log (if relevant):
Guide used: (Mention if you followed a guide)
File: (File with issue - with FULL path)
Emulator: (Name of emulator - if applicable)
Attachment of config files: (PLEASE USE PASTEBIN.COM FOR LARGE LOGS)
How to replicate the problem: