I tried everything as well.....and just gave up after my post was not replied in regards to the exact issue you have. DTM worked for my 7510 until I upgraded to a 7520 two months later......which worked for about two weeks.
When you launch DTM, check the 'COnnections Manager' and see if you can manually detect your BB. it worked for me but DTM itself would not detect my device.
__________________
-wL
|