401.2 error authentication for a subdirectory in IIS7, works in VS 2008

I get:
Server Error in '/dl' Application
Access is denied.
This application works fine within Visual Studio 2008, it's when I copy the application to the server running IIS 7.
<system.web>
  ...snip...
  <authentication mode="Windows" />
  ...snip...
</system.web>
<location path="admin">
    <system.web>
      <authorization>
        <allow users="mydomain\myuser" />
        <deny users="*" />
      </authorization>
    </system.web>
  </location>
I verified that it works properly in VS 2008; if I change the user to someone else, it doesn't work for me.  My guess is this has something to d ...