Is the "serial number" showing up in the initial AFPD screen? If it is, then it's reading the cable okay... It may just not be seeing your radio... The most likely culprit in that case (Assuming its not a bad cable) is the "phono" plug.. Make sure it's snapped in tight... I've had my come lose on several occasions and thought I had a problem when in fact it was just not plugged in tight. (to the adaptor, not the adaptor plugged into the radio)