[Konstantinos]

The unknown command message is shown even if a run time error occurs in the command's code, not only if it returns 0.

I guess the problem is in SendClientMessageToAdmins, a loop which the variable of it exceeds the valid bounds of an array (the one for checking the admin's level). Anyways, you can load crashdetect plugin and compile with debug info and it'll show you exactly what caused it.