I had this same problem with my HV20, and FCE, I could not get it to work for days then all of a sudden it started working, and has ever since. I have no idea what did it unfortunately.
You probably already have done this but just make sure anyways.
-The capture mode is in the same format as what you want to upload, so FCP recognizes an HDV camera and not a DV one
-The footage you are currently on on the tape is the same format
-The project settings match the video you are trying to import
-The output mode on the camera is set to HDV/DV
Also try capturing live and see if that works. When mine wouldn't work it would still capture like that for some reason.
Again I have no idea what fixed my problem, it just started working one day. Can you capture into imove?