Outbound - Proxy through client access server

Hi there,
Just wondering if someone has that situation that I’m currently have... Migration done between 2010-2013

Was using Edge 2010 and now I want to use the Outbound/Inbound Mail flow Proxy through client access server,,,

My Environment:
1 CAS 2013 on the DMZ (AD-SITE1)
2 servers Combine role (CAS, Mailbox) DAG back-end.. (AD-SITE-2)
1 Send Connectors (internet with the Proxy through client access server to $true).

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Mail-Flow Inbound:
Firewall --> CAS 2013 (DMZ) --> Mailbox,CAS 2013 (LAN) this is Working GREAT. (I can see my hops correctly 
and If I configure to $false just can't get it. $true working Fine)

NOW my Mail-Flow Outbound:

Using my internet send Connector MX resolution or using Smart host same result

Scenarios 1:
Mailbox,cas (combine role) 2013 --> Fiwerall with Proxy through client access server $true or $false = Working

Scenarios 2: (Here is my problem)
Mailbox,cas (combine role) 2013 --> Firewall Block SMTP (my back-End server to test if it proxy or not) and let pass only CAS in the DMZ with 
Proxy through client access server to $true = The Mail is Queued. I allow my back-End SMTP outbound Email pass without using my CAS in the DMZ. 
At that point I told myself is it because of the combined role? So I build up a second environment with only 1 Mailbox and 1 CAS (no combine role)
I do have the same result!! Telnet on all ports working fine… I do not have any Event saying Proxy is in trouble,,, it just seem that My Internet 
Send Connectors cannot connect using the proxy for my Outbound Mail-Flow to my DMZ CAS! I turned my trouble shooting Mail-Flow to Verbose and nothing 
special in the logs just normal flows.

Any though?

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Yanick |MCSE|MCP+I|MCTS Exchange 2007|MCITP Exchange 2010