Volvo C70 and aux jack

I tried to plug in my 1st Generation iPhone using the Aux jack, and it does not connect to the car stereo system. I make sure the car audio system is set to Aux mode, and still no music. Yes, I have the adapter that extends the recessed audio jack that the old iphone has. When I plug in my iphone 3G, the connection works fine. Any ideas as to why this is happening?

The USB port does not work also.