You have registered an interceptor and then tried to send a command to it. This is not what interceptors are for. The idea is that you set up an interceptor to catch all lighting plugin messages, then when a message is sent to a light they are also sent to the target in your interceptor.
My wiki page may be of some use, as I hacked something together which does what you are trying to achieve.http://wiki.linuxmce.org/index.php/User:Chrisbirkinshaw
BTW why do you want to do this? If you just want to run code on events then you can already do this through the web admin respond to events pages. If you have a case for which this does not work I am interested as I am trying to collect all such cases and propose some changes.