Well, if the tuner is getting power from the Data port, and the computer is interfacing with the tuner, the only other thing is to make sure that your pins are all pushed into the data port. Sometimes they get loose, so you may want to check.

When you select your com port, it should almost immediately find the tuner. You may also want to try to switch USB ports to see if that fixes the problem. I remember having that trouble when I first got mine.