Unable to return search results through SPML sample page (4341334)

When attempting to return search results via the SPML sample test page the following error is displayed:

Administration Policy returned an error. Attempted to perform an unauthorized operation

Follow the steps below to ensure that asp.net impersonation is set on the SPML provider page

1. Open Internet Information Services (IIS) Manager on the SPML provider host
2. Expand the host name
3. Expand Sites
4. Expand Default Web Site
5. Left click on the "ARServerSPML" site
6. Click on "Authentication" in the middle pane
7. Ensure that ASP.NET impersonation is Enabled