LYNC2013- Reverse Proxy not working on single F5 LTM

Hello all,

I have a single F5 unit configured to work as Reverse proxy for LYNC 2013. It is not working.

I am using LYNC 2013 I APP template and putting all the details correctly for URL etc I have also added the manual front end servers for port 4443 under it. When tested I can telnet the servers from external LTM interface on port 4443 but the reverse proxy is not working. I do not get DL expansion/ dialin page when accessed from internet. The IRULE has been checked and found to be correct. Actually the same configuraiton I have on another region which is working fine. Can someone advise what is going wrong here? What I suspect is that the HLB is not forwarding the request on port 4443 on front end. Thanks for all your advise. Let me know in case any additional details will be needed.