Trouble with Spotify in car - Iphone 3Gs

[user125]

Hello. I am a spotify Premium user, with an Iphone 3Gs. I have Premium in part to be able to use the application in my car. I have a USB auxiliary connection that allows me to hook up ipods/iphones to my car to play music. However, when I try and use Spotify with my IPhone, an error message comes up in my car reading, "USB No Song," or "unsupported." I can play songs from my ITunes and have tested it with IPhones from other friends and they can use Premium without fail in my car.

Does anybody know of any solutions to this problem? Is it something specific to an IPhone 3Gs?