Why doesn't Smart Talk BYOT sim work in my Lenovo Tab2 A 10-70?

[AC Question]

I bought the Straight Talk BYOT sim kit at wal-mart yesterday. Put the tiniest sim for AT&T into the tablet as indicated. The kit said the sim would fit the card slot exactly. Not really. A little small. The sim just went to the bottom, no click. Followed instructions to reboot, then reboot again. Nothing happened. No indication that anything installed or was ready. We thought maybe the card was in wrong. It wasn't. Then we thought maybe it was one of the slightly bigger cards. It took an hour to get the other mini card out. Not spring loaded like other minis. Neither of the bigger cards would fit, no matter what we did. It looks like they would, but no way. Very frustrating! The tablet IS GSM which is one of the requirements for use with Straight Talk.