feh won't make a montage in a script

[David Liontooth <liontooth@cogweb.net>]

I'm using feh, an image viewing utility, to make a montage of thumbnails,
with this command in a bash script:

        feh -m -W 1024 $FIL.img/$THUMBS/*.jpg -O $FIL.jpg

The man page explains,

       -O FILE 

"Just save the created montage to FILE without displaying it (use in
scripts)."

When I run the script, I get this:

        feh ERROR: Can't open X display. It *is* running, yeah?

X is running, but so what? I'd like to run the script when it's not. If I
run the script from the command line, it works.

This could just be a bug, cf.
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=373209

Dave