"rsAccessDenied" Error when Anonymous User from a Virtual directory access the Reporting S

Hi,
My setup is that i have a IIS virtual directory with Anonymous user (
enable anonymous ) to access Reporting Server. Both are in same server
anyway.
I have a web page in the virtual directory with url link to the
Reprting Server.
if I grant this anonymous user with admin privilege , then it works.
Why ' what kind of privilege is needed in fact ? There are some clue
but i dont know how to intepret.
The error log from Event log is as below:
Event Type: Error
Event Source: DCOM
Event Category: None
Event ID: 10016
Date: 18/01/2006
Time: 10:41:23
User: NT AUTHORITY\NETWORK SERVICE
Computer: SVR071
Description:
The application-specific permission settings do not grant Local
Activation permission for the COM Server application with CLSID
{BA126AD1-2166-11D1-B1D0-00805FC1270E}
to the user NT AUTHORITY\NETWORK SERVICE SID (S-1-5-20). This
security permission can be modified using the Component Services
administrative tool.
For more information, see Help and Support Center at
http://go.microsoft.com/fwlink/events.asp.What is the configured identity of the 'ReportServer' service? Is it
interactive user? What is the security configuration for the
ReportServer virtual directory? What is the security configuration for
connecting to your SQL serrver?
If you're accessing the virutal directory as an anonymous user and the
RS service is configured to run as the interactive user, then the
interactive user (in this case anonymous) would need priviledges to
connect to SQL and any other necessary resources.
Andy Potter