I had a simillar problem with my Dension kit (I-20) and it started working after pushing both connectors connected to the little "converter board" which plugs into the wire coming from the CD changer connection to the Dension cradle.
I'd suggest to turn off the ignition so the radio is off , turn on the igniton and radio and see if the connectors are the problem (it seems on some of the boards the plastic protection for the plugs overlaps the area where the plug should seat flush).
I still had sound quality issues (highs not as clear as CD) and will probably end up using the AUX input and a custom integration with a remote control as I'd like to keep my CD Changer and Sirius just in case
- Jan