If the user is validated, and all looks ok, but the drive does not Mount?
Normally this is because the client is started with administrator rights.
Do not do this. The client will start under different credentials than the user, and due to security, the drive will NOT mount correctly
Your icon could look like this.
If so rightclick on the icon and, select probertite, and compatibility.
Check that the setting under "Change setting for all users" is also "not set"