Err 01 on Canon T2i + Sigma 28mm 1.8
So I picked up a used lens off of eBay that wasn't as tight as my 50mm. I ended up with a Sigma 28mm 1.8 but it keeps giving me Error 01. I cleaned the contacts with a cotton swab and rubbing alcohol but it still does not work. The lens works fine and will take pictures + autofocus. The pictures save, but the error pops right up and don't let me do anything. However, the pictures save in movie mode and it doesn't give me the error—but I'd rather use the eyepiece.
I've read online that some people have had to ship it to Sigma for a new chip or firmware, but I'm having a hard time figuring out if this is the problem.