Why is only one sim working in my phone?

[AC Question]

I have a Honor x and for the past couple weeks my sim 2 slot has not been showing the sim I have inserted in there. This problem was on and off for months but now the sim simply will not pick up.

 

[the tall guy]

What happens if you swap the sims around, does the dead sim work in the slot 1? if so then the slot 2 is the issue, might need to look into getting it repaired.