Some users have been recieving 401 Error when attempting to run Test-OutlookWebServices from the CAS server. The below articles talks about why IIS returns this error.
http://support.microsoft.com/?id=896861
You can test this by attemtping to access the server in the following way:
https://netbiosname/Autodiscover/Autodiscover.xml :It will prompt for credentials. After prompting a couple of times we get the following error:Error: [...]