12209 Forefront TMG requires authorization to fulfill the request. Access to the Web Proxy filter is denied

When setting up Avaya SAL (Secure Access Link) Gateway with Proxy.  The connection to Remote Servers would not establish, and Proxy server (a Microsoft Forefront TMG Server) logs shows many SSL-tunnel both Denied and Allowed messages alternating each other.  Had to open firewall to allow the SAL gateway direct Internet Outbound Access.  It seems to be that Microsoft Forefront TMG having  issue with some 3rd party applications going through the proxy.  It has no problem for Firefox going through the same proxy server..