SSRS 2014 Exec Log gives the Service Account as UserName instead of Actual User name

I am using the below query for accessing the Users who are using the Application Reports. SSRS 2014 gives the Service Account(IIS Account used for Application) as User Name instead of Actual User name. USE ReportServer; GO SELECT el2.username, el2.InstanceName, el2.ReportPath, el2.TimeStart, el2.TimeEnd, el2.[Status], isnull(el2.Parameters, 'N/A') as Parameters FROM ExecutionLog2 el2 GO Can you please let me know why I am not able to see exact username who accessed the Report instead why I am seeing the Service Account in the place of User Name exactly. There is only one DISTINCT RequestType which is Interactive. Where as when we read IIS logs using Log parser it does contain the User Name individually Thanks