AOR '' not found for endpoint '200'

FreePBX Endpoints
1

I am having a trouble for days to figure out how to configure pjsip trunk. I gave up on further searching and I know that this may be asked often but I am in a dead end.

Asterisk still showing this error:

 WARNING[29555]: res_pjsip_registrar.c:1068 find_registrar_aor: AOR '' not found for endpoint '200' (<ip address of other PBX>)

So the blank AOR is causing the problem, but how to I assign proper AOR for 200 endpoint?

My trunk Setting:

Trunk Name : 200
Authentication:  None
Registration : None
SIP Server: <ip address of other PBX>

So what else I need to fill

Thanks for guiding