Why won't my dual SIM work?

[Swizz kidd]

My Samsung j2 uses dual SIM but when I insert two SIM cards only SIM 2 works. SIM 1 says emergency calls only. Can someone help me out please

 

[B. Diddy]

Welcome to Android Central! What's the exact model number, and which carrier is the SIM in slot 1 from? You have to make sure the phone supports the network bands from that carrier.