Hi, I have a problem with my Canon EOS 300D and an old Quantaray 80-300mm lens (I bought it 1995, need to check the correct name). The lens works fine on my EOS 500 (which it is supposed to be made for since it's a film camera) but when I want to use it on my 300D I can make one, sometimes two shots and then the camera tells me ERR 99. All other "analog" lenses work fine on my 300D. Can anybody tell me if this is a general problem or if may be just the lens contacts are dirty or something along these lines? Thanks for help.