I have a Sigma 70-300 APO MacroSuper that doesn’t seem to want to work with my Canon 20D. Any help or expertise is appreciated!

I got the lens a while ago and haven’t had the chance to play around with it much. I tried last night and it would take 1 or 2 pictures before giving the Error 99 code. This is a general code for “something not right”. Only way to clear it is to remove the battery and wait. Sometimes it will take a couple pictures before the code, sometimes it won’t take any.

The lenses autofocus function does not work either though I don’t really care as long as I can use manual. Some research has gave me info in that my camera might just not be compatible, or that the lens is not compatible.

Anyone ever experience this?