Well that’s a different problem 
.
Everything, including boot and LTE firmware, upgraded? See http://forum.mikrotik.com/t/no-lte-connection-with-sxt-nor-atl-but-within-range-of-tower-bands-13-66/169189/1
Some questions:
Do you actually have a PIN on your SIM?
Other thing is try selecting ONLY “LTE” as the network type (e.g. uncheck 3G/GSM/etc)
Does this only happen if your specify “bands” to use? If you remove the band selection, does the error go away?
I generally start with the software…But it could also be a bad SIM, especially if outdoors. Try re-seating or putting tape on back to make it “thicker” to press better on the the pins.