Xcalibrator 2 problems help please?

Ok I just ordered a xcal 2 for my 99gt. I plugged it into my diagnostics port and it would not power up, tried it on my friends gt same thing. But I plug it into my usb port on laptop and it powers up but when i try to tune it it says voltage to low try agian. Is it a bad tuner or and i missing somthing? Any one with any comments I would apprciate it thanks.

Ok I called sct and thier are telling me it s voltage problem with the cars. And to try it on another ford. He said it could be a wiring problem somewhere or somthing came undone. What is the deal is it broke or what would be some place to check for faulty wiring ect that would casue this? Like I said when usb port is plugged in it powers up fine.