Hi Armin, there are some instructions in the help file here:
http://moi3d.com/2.0/docs/moi_command_reference11.htm#shortcutkeys

To create a new keyboard shortcut you actually type in a text label, like if you want to make a shortcut for Ctrl+B, when you set up the shortcut key you don't actually hold down control and push B, you instead actually type in the text "Ctrl+B" there.

In the future at some point I'll probably try and set it up the way you were probably expecting where you actually push the shortcut key combination to define it rather than typing in the text label like you currently do.

- Michael