internal GTM integrate with external LTM

In this lab environment I dont have WAN links, but the idea is indeed to have two WAN links connected and publish the Wide IP using two public IP addresses. I understand the logic and have implemented it several times. The only thing is that I ran into this technical issue using an internal DNS integrated with an external LTM that currently is not able to verify the status of the virtual servers configured and active on the external LTM device. The server link is green as you can see above but it does not discover any of the virtual servers of the external LTM nor the status of the virtual servers.

Maybe perhaps this is just a small issue using VMware I really dont understand, but I understand correctly this setup should work accordingly.