Windows Agent proxy settings

Windows Agent proxy settings

I am trying to test this out with a view to purchase 
But I cannot get a windows client to report 
I have two proxy to try via, neither work  - I see nothing in the proxy logs 

The agent log shows 
tEx : Site24x7 Server -> plus.site24x7.com 
2015/04/28  10:14:30:868 InternetSendRequestEx : Site24x7 Server Port-> 443 
2015/04/28  10:14:30:868 InternetSendRequestEx :  Error in WinHttpSendRequest [plus.site24x7.com] -> 12007 
2015/04/28  10:14:30:868 HttpGetLastError: The server name could not be resolved.

All sites required are unblocked as too are 443 & 80 ports 
The only way I've managed to get it to report is to move onto a public line with no proxy 
Im not even sure the proxy settings on the client are registering 
Has anyone else had this issue ?