Error when SSRS Report Running from a .Net Report Viewer

When report viewer report added to the .Net application and report path is set to a deployed report to the report server following error message will occur.

The permissions granted to user '<DOMAIN>\IUSR_<DOMAIN>' are insufficient for performing this operation. (rsAccessDenied)

1. Open Internet Explorer.
2. Type the following in the Address bar:
   http:// application-tier/Reports/Pages/Folder.aspx 
   You can find the name of the report server by opening Team Explorer, expanding the Reports node, and viewing the properties of a report.
3. Click the Properties tab and then click New Role Assignment.
4. In Group or User Name, and add the Windows logon name for the person you want to add to this group.
5. In Role, select Content Manager, and then click OK.