& ldquo; No Source Available & rdquo; - Visual Studio Debugging (even when symbols have been loaded)


I have set up Visual Studio 2012 Professional to download debug symbols. It is set up correctly and the symbols have downloaded.

I get to the line of code I wish to step into:

bool result = Membership.ValidateUser("user", "password");

I right click on it and choose step into specific-->Membership.ValidateUser()

Then a tab opens in Visual Studio saying:

No Source Available - There is no source code available for the current location

Membership.ValidateUser() is in the System.Web.Security namespace which is in the System.Web.dll. If I open up the Modules window I can clearly see that the symbols for this assembly have been downloaded.

If the symbols are there, why am I not able to step into the source code?

Source stepping is only available for RTM or SP releases. See PDB files for .NET Framework 3.5 SP1 not available! (i.e. System.Web.pdb 2.0.50727.4016).