RPC Proxy can't be pinged.

Hi

I am in the middle of an Office 365 cutover migration and the company used autodiscover.company.com for the Outlook Anywhere URL.

I have change it, but I can't get it to work.

They have an ISA in front. And this is Exchange 2007.

I keep getting

Attempting to ping RPC proxy anywhere.domain.com.
	RPC Proxy can't be pinged.
	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. Elapsed Time: 169 ms.  Any ideas? thanks.