I found out that when I set the default protocol in the View Connection Manager to be PCoIP instead of RDP, some thin-clients and view clients cannot log in to their virtual desktop. They get a visual or screen initialization error.
I then realise that the older were only RDP based and there was no "Protocol" auto switching.
I had to set the Pool to run default RDP.
I also tried using a "thinapp" verion of the view client and some times it goes into a blank screen when I force a RDP connection.
If I try the default PCoIP settings it always worked.
Is there a way to set to detect the client's protocol, such that if PCoIP fails, use RDP ?