BPC SSRS Reports configuration

Hi,

I am trying to enable auditing feature for BPC. And even after enabling auditing and published reports from BPC for Admin, am not able to pull reports and am getting below error.

• An error has occurred during report processing.
  • Cannot impersonate user for data source 'OSoftDataSourceAudit'.
    • Log on failed.
      • For more information about this error navigate to the report server on the local server machine, or enable remote errors

So when I see SSRS, I don't see any of my BPC appsets. And more over I don't see that SSRS Service running as well.

So, my question is how to active SSRS for BPC once BPC is installed and running for a while. I couldn't find document on this.

Thank you so much in advance.