I just picked up a hard top for my 72 350SL.....it has the cable plug that fits into the side plug.....but the rear window doesn't have those tell-tale wires in the glass that a normal defroster has..... When I hit the defrost button on the dash...nothing really happens.

1. Do I actually have a defroster....with no wires in the glass?

2. How come it don't work?

3. Should I just continue to use my manual defroster....(hand and a rag??)_

any help would be great.
thanks