citrix with NAT, possible?

I'm trying to have the following environment working:

• APM app publishing for XenApp 6.5
• 2 XML broker and 2 ICA servers
• the citrix environment is in a vCould with NAT. BIGIP sees the NATed addresses of all servers.

The broker part is working well as I get the apps publish on the webtop. The issue is when the receiver starts and the APM gets the XML file for app connection, we see inside that file following entries that are problematic

    
      :1494
[...]
      :443
[..]
    

The result is that packet trace for the Receiver to APM shows only a couple of TLS handshakes without app data, then the APM terminates them. The receiver puts an error "network issue" (not SSL, as we have fixed all certificate/SSL issues previously). I guess it's because it cannot interpret/rewrite that XML file. We must use NAT because of vCloud/topology and I'm stuck here. Any idea?

Thanks! Alexandre