Double click Amac Keylogger (Pro) and try the hot key again (default Ctr+Alt+M).
1. If you are using AZERTY keyboard, try hotkey Ctrl + Alt + ,
"," is the same key of "?" at the right of "n"
2. If you have a PC keyboard, try to use Win+Alt+M or Ctrl+Win+M
Please minimize other windows and show the desktop when you try the hotkey.
If you have changed the hotkey, you should use your key.
Make sure you check the option "Run Amac Keylogger at Mac startup" in Settings - General tab.