When using a thin client and manually entering a domain name, the name must be entered in upper case letters for SSO to function.
Details
When you are selecting a VDM Connection Server to connect to using SSO, if you manually enter the domain name and enter lower case characters, SSO fails. All of the characters you enter must match the characters in the domain name as it appears in the drop down menu.
Solution
Either select the VDM Connection Server using the drop down menu or check the domain name that you enter against the domain name in the menu to make sure all characters match.