Erm can you remote link to your sig? I'll investigate when I get five minutes.
We try to stop sigs that are uploaded onto the forum from being too big by dimensions or memory for obvious reasons (ie so they don't affect the running of the site) but you should be able to remote link (ie from photobucket?)
if my Dusan sig works, any sig should work surely? (although mine is rather basic tbh) but it's not compressed or anything, it's just in it's as it comes settings and uploaded to the site direct.