IAX Trunk video problem

I have setup IAX trunk between two server (asterisk version and, both with Openvox TDM card) with video support enabled. Only ulaw and H264 are allowed on both side. There is one grandstream GXV3140 on each side. Video call via this trunk doesn’t work when the option trunk = yes is presented in the trunk option. Besides no video, both side will hear some clicking noise. Once the trunk = yes option is taken out, both side can see video without any problem. Anyone know what’s wrong and how to fix it?

Hi, anyone?