"No data is available for the requested resource." err

While building a .asp file that will serve up XMLized SQL recordsets,
I came into the following error in XSL.Error "No data is available for
the requested resource." Google excursions turn up red herrings.

Same error, of course, comes up while using XSL's document() function
or just including the .asp.

Yes, the .asp does work if I just visit it in the browser. Also, I'm
remotely calling .asp (with javascript) all over the site with no
problems.

Has anyone run into anything like this? Can anyone give me a better
idea of what is actually causing the problem?