Can't get connection b/w PDA and desktop

What operating system are you using? there are issues with windows Vista that can be resolved through their website......

Is the charging light on? Even with the light on, you may not be getting a good contact with the connector. IMHO the Garmin iQue 3600 USB cradle has the worst connector design in all gadgets I have known and used. You have to drop the PAD vertically into the connector and then lean it back to "lock" it in place. To remove it, you have to reverse the procedure. If you're not handling it gentle enough, you may bent one of the little bouncy metal contacts (making it shorter than the the rest). Look closely at the pins and make sure they are aligned in one straight line and all with same height. At one time, I have to press it tight against the base to ensure a firm contact thru out the whole sync process. Hit the sync button, if you hear the "sync sound" right away, you are ok. Otherwise, cancel and do it again. If one of the pins is shorter than the other, try to "pull" it up with a small needle nose plyer. You can also use dental-floss to wrap around the pin and pull it up. If all fails, you can start looking for a new charge/sync cradle...