jQuery IE and reverse proxy

jQuery IE and reverse proxy

Dear All,
 
I have set up a reverse proxy for a wordpress blog that is using the theme mystique.
 
When I use IE to connect directly to the blog the theme works fine and loads ie7.css
When I connect through the reverse proxy to the blog the theme does not load the ie7.css
 
From what I can work out it looks like the person who wrote it is using jquery to determine the browser type.
 
Any ideas why jquery would fail when passed through a reverse proxy?
 
All help very much appreciated.
 
Yours sincerely
 
David Ruwoldt