Outlook Anywhere - HTTP 403 forbidden

We are in the process of migrating from Exchange 2007 to Exchange 2010 but I can't get Outlook anywhere to work. When I run ExRCA, I get the following error during Testing HTTP Authentication Methods:

I get the 403 error internally as well if I try to go directly to the https://internalmailservername.company.com/rpc

All other services such as autodiscover and activesync work just fine. I am using a wildcard cert. I have tried setting the OutlookProvider certprincipalname for EXPR but still no luck. IIS configuration follows http://msexchangeguru.com/2010/10/05/autodiscover/. I'm using Basic Authentication for Outlook Anywhere. All traffic to the CAS array is routed through a Netscaler.

Any ideas?

Testing HTTP Authentication Methods for URL https://mail.domain.com/rpc/rpcproxy.dll?outlook.domain.com:6002.
	The HTTP authentication test failed.
	Image may be NSFW. Clik here to view. Additional Details   An HTTP 403 forbidden response was received. The response appears to have come from Unknown. Body of the response: You do not have permission to view this directory or page.