...it's your cable!
After much angst I figured out that (at least some of) the crappy USB to Micro USB that AT&T sells in their stores are ONLY good for power. I bought the combo wall plug/car plug kit (the one with the blue light). Once I switched to the one that came with my phone it worked perfectly.
The symptom is no recognition whatsoever when you plug your phone into your computer. If that's been happening try a different cable.
After much angst I figured out that (at least some of) the crappy USB to Micro USB that AT&T sells in their stores are ONLY good for power. I bought the combo wall plug/car plug kit (the one with the blue light). Once I switched to the one that came with my phone it worked perfectly.
The symptom is no recognition whatsoever when you plug your phone into your computer. If that's been happening try a different cable.