Forms Authentication and Unattended Report Execution

I have implemented forms authentication security extension as described in the MSDN whitepaper "Using Forms Authentication in Reporting Services" and it works fine. However, I ran into problems trying to create scheduled execution snapshot for a report when it fails with unable to authenticate. How do I configure RS to authenticate for unattended execution with forms authentication?

Thanks,Please disregard this one. Stopping and restarting the ReportServerService resolved the issue.