The permissions granted to user 'DOMAIN\username' are insufficient for performing this operation. (rsAccessDenied) in OCS 2007 R2 Monitoring Server Reports

Hi, I'm trying to access the reports from OCS 2007 R2, but cannot get any further than the First page (Monitoring Server Reports). (Examplehere)

When I click one of the reports, I get the error:

The permissions granted to user 'DOMAIN\username' are insufficient for performing this operation. (rsAccessDenied)

I'm not sure where to set the appropriate user access.

Thanks in advance.