Can't hit breakpoint in .ashx file

All:

To my VS2012 solution, I added an "Existing Website".   This website contains nothing more than a single C# ASP.Net generic handler file (i.e. a .ashx file).  I set a breakpoint in the ProcessRequest() method, but it never gets hit.  When I launch Visual Studio (as Administrator) and start the website, the breakpoint becomes disabled with a message that the "symbols could not be loaded".  What symbols?  The generic handler is compiled at runtime.  Sure enough the breakpoint isn't hit but the code is successfully executed.

What step am I missing to allow the execution to halt at the breakpoint?

Thanks for your help,

Bill

Bill Davidson