Blank Reporting Workspace for Report Operator user role

Hi,

I've made a new Report Operator user role, however the users in this user role have a blank Reporting Workspace. I've added the identity ID of the user role in a new Role Assignment on the Reporting Server. When I click View Scheduled Reports on the right hand side I get the following error:

Date: 25/07/2013 12:05:22
Application: Operations Manager
Application Version: 7.0.9538.0
Severity: Error
Message: Report subscription list could not be loaded.

System.Web.Services.Protocols.SoapException: An error occurred when invoking the authorization extension. ---> Microsoft.ReportingServices.Diagnostics.Utilities.AuthorizationExtensionException: An error occurred when invoking the authorization extension. ---> System.Exception: For more information about this error navigate to the report server on the local server machine, or enable remote errors
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
   at Microsoft.EnterpriseManagement.Mom.Internal.UI.Reporting.ReportingService.ReportingService2005.ListSubscriptions(String Report, String Owner)
   at Microsoft.EnterpriseManagement.Mom.Internal.UI.Reporting.ManagementGroupReporting.GetSubscriptions(String owner)
   at Microsoft.EnterpriseManagement.Mom.Internal.UI.Reporting.Views.ReportSubscriptionsView.ReportSubscriptionsView.LoadSubscriptionsJob(Object sender, ConsoleJobEventArgs args)

Thanks!