I agree with Rice Nuker, check to see if the inline fuse is blown or not seated in the plug properly. A lot of times the fuse is located in the plug itself (sits just behind the tip) and all you have to do to access it is to turn the tip. If you want to install a under dash port it's very easy to do. All you'll have is 2 wires, one can go over to your fuse box to pick up the positive connection or you can splice into the wire going to your exsisting lighter (I prefer running a wire to the fuse box as I don't like splicing ionto the harness) and the other will ground to the dash metal. Anyway good like iand if you have any more electrical questions feel free to PM me, I am an Electronics Technician by trade.
Glenn