Radio goes dead when i close the door. Help!

I just installed an aftermarket Blaupunkt head unit in my 1986 300E. Its my first car and i'm by no means an expert electrician. I got it wired in all right and when i started the car the radio turned on and played fine but to my surprise, when i shut the driver door the car cut the power to the radio.
I experimented with starting the car with the door closed: no power to the radio. After examining the little push-in sticks that sense when the door is closed, I found that the head unit still has power when i press the top stick but it goes dead when i press in the bottom one. I'm clueless as to what this means or how to fix it but i do know that i'd like to be able to listen to the radio with the door closed.
If there's anyone out there who has had this problem or knows how to deal with it please post a response. Thanks.

Jordie

[Ashman]

sounds to me like you have the ignition wire for the radio wired to the dome light switch or the alarm door pin. you need to check for a wire that turns on whent he ignition key is turned to the on position. And goes off when the key is off.

Alon

[G-Benz]

I concur...I don't know how many times I've read a thread where someone attempts to find a hot lead with the door (predictably) open. Why the door lead is so prominently featured in the wiring harness is anybody's guess...

...it does make for interesting results though... :p