While supporting Microsoft Dynamics for CRM, I was recently quite surprised to have to associate role membership permissions within Reporting Services for users of what I could only assume are extended properties, because up to this point I had thought permissions for reporting services were handled on the database engine side only. However, under OrganisationName_MSCRM and properties you will see the following Role Assignment options.
The link to your own Reporting Services instance should be the following for the above page:
You might also run into this error, and the above Role configuration should help you fix that:
Reporting Services Error
• The permissions granted to user 'USERNAME' are insufficient for performing this operation. (rsAccessDenied) Get Online Help
SQL Server Reporting Services