I activated my wife's Moto x with a nano SIM out of the kit just fine. Stupid question is did you set the apn settings? Maybe the SIM went bad. My kit was all messed up, I got two AT&T nano Sims and two tmo regular/micro Sims.
Sent from my MB886 using XDA Premium 4 mobile app
"But WHY THE RUM??!!"
With one custom rom or another.....