Battery cover - Front

I purchased a Dell Aero (Unlocked) from Masterdeals via Amazon.com and it did not come with the Mini USB to 3.5mm adapter. This might be due to it being a European (Turkish?) version. (It also came with a charger with the European plug.)I have tried a couple of generic adapters I found on the internet, but they don't work on my Aero. The audio will not pass through the adapter to the headphones, instead it continues out the phone speaker. Do you think I have a defective Aero, or is the adapter shown as image 6 of 71 in your Aero breakdown column a proprietary Mini USB plug or should a generic adapter work? And, just in case, where can I purchase the one in your article? Thanks very much.