Mod Rewriting Image Location Not Working Very Well

Question

Hey, I'm trying to mod rewrite the image locations on my site, I'm just using this :

rewriteRule ^thumbs/(.*)$ http://site2.com/thumbs/$1 [L] 

so that I can redirect all image requests going from

http://site1.com/thumbs/something to http://site2.com/thumbs/something

But only some of the images are loading, and not all of them.

The image appear broken, but when I go to them directly they work.

Thanks!