jenkins attachments - what is the syntax?

I'm trying to have Jenkins attach a file or set of files to the email notification that the job has completed. I keep getting an error along the lines of:

Sending email for trigger: Success ERROR: Error accessing files to attach: Expecting Ant GLOB pattern, but saw C:\p\p\etc\\\*\*\\\*.html.

See Fileset syntax

And yes I've looked at that site and tried every variation I could think of:

/ instead of \
../\*\*
../\*\*/\*.html
removing C:

What is the Ant GLOB pattern I'm missing here?

thanks, Scott