help with mod rewrite needed

There is a program called webcollage that fetches images from random
web sites and posts them into a person's screen as a collage.
I'd like to redirect this program to just a single image of my
choice.
I've done the following using mod_rewrite and it doesn't seem to work.
Nothing gets rewritten.
Any help appreciated, I'm trying to be a photographer, not system
admin in my retirement. Thanks!

--httpd.conf extract:

RewriteEngine on
RewriteCond %{HTTP_USER_AGENT} ^webcollage.*
RewriteRule ^(.*) robertdfeinman_com.jpg [L]

RewriteLogLevel 7
RewriteLog "/export/home/rdf/rewrite.log"

--sample from apache log
66.232.198.52 - - [03/Jan/2004:10:52:53 -0500] "GET
/panoramic_horizontal/hawaii/kauai/pages/kauai_beach_hpan.html
HTTP/1.0" 200 2980 "http://www.altavista.com/image/randomlink"
"webcollage/1.107"

--contents of rewrite.log
66.114.64.63 - - [03/Jan/2004:11:48:01 -0500] [66.114.64.63/sid#178040]
[rid#2ab040/initial] (2) init rewrite engine with requested uri
/disco3iv/html/disco3iv.xml
66.114.64.63 - - [03/Jan/2004:11:48:01 -0500] [66.114.64.63/sid#178040]
[rid#2ab040/initial] (3) applying pattern '^(.*)' to uri
'/disco3iv/html/disco3iv.xml'
66.114.64.63 - - [03/Jan/2004:11:48:01 -0500] [66.114.64.63/sid#178040]
[rid#2ab040/initial] (4) RewriteCond: input='Java1.2.2'
pattern='^webcollage.*' => not-matched
66.114.64.63 - - [03/Jan/2004:11:48:01 -0500] [66.114.64.63/sid#178040]
[rid#2ab040/initial] (1) pass through /disco3iv/html/disco3iv.xml

-- the contents of the rewrite.log file get created when I restart
the apache server, but nothing else seems to get added.
66.114.64.63 is the IP of the web server.
I have no idea what all the .xml stuff is.

--
Robert D Feinman
robertdfeinman.TakeThisOut@netscape.net
Landscapes, Cityscapes, Panoramas and Photoshop Tips
http://robertdfeinman.com