Older Canon EF 80-200 error 99 question

I've read almost all there is to read about the Error 99 out there, and I have one unanswered question.

I just acquired a Canon EF 80-200, and the box has the original sticker on it, showing the date as 1994. When I put it on my XT, it's hit or miss whether I can take a picture, or get the Error 99. AF and aperture are working, until I take a pic and get the error 99. I figured it had the ribbon cable problem, or one of the other hardware related issues.

I just put the lens on a few other film bodies; EOS620, Rebel K2, and a Rebel G. The K2 has film in it, so I took 2 shots, and both seemed to have went well. The 620 and the G don't have film, and I shot about 30 pics in each with the lens, and the cameras didn't hiccup.

So now it's pretty obvious that it's something in the communication between the lens and body when it come to the dSLR (Rebel XT). In your best guess, would it be a hardware, or a software issue, and can it be corrected? If so, do you think Canon would correct this for me?

I had this problem with the original EF 80-200mm f/4.5-5.6 lens too. It was a communication error. After all of those years, the electrical contacts had oxidized. I took a soft cloth, moistened it with a drop of isopropyl alcohol and rubbed the contacts. The lens worked fine after.

I cleaned the contacts on both the lens and the body with some Deoxit, and still get the err99, but only on the dSLR, the film cameras are happy to snap away with the lens.

The lens autofocuses pretty quickly, and I'm not having any other issues with it, just doesn't want to work on the XT...?

That is odd that it works fine with your film bodies, but not the XT. Although the little plastic 80-200s don't look fancy, they actually work reasonably well. Stopped down a a little, and using a hood, they are reasonably sharp and fit in a jacket pocket.

Maybe I'll give Canon a call tomorrow, see if I can find something out.