Using 100mm/2.8 USM on older EOS Body no AF

[AnselAdams4x5]

I just purchased a 100mm/2.8 USM Macro lens. Works perfectly on my 6D. It does not respond at all on my film EOS A2. I have three other EF lenses, 17-40 L, 28-135 IS and 70-300 IS. All of these other lenses work fine with my film EOS A2. Does anybody know why?

[AnselAdams4x5]

Battery indicator shows good and all my zooms work fine on old A2

[AnselAdams4x5]

Thanks for your thoughts 

[deebatman316]

Does the camera display F/00 as the aperture in the viewfinder. Or does it display the actual aperture.

[AnselAdams4x5 · Accepted solution]

Was suspect that was the cause since lens worked fine on 6D and other zooms worked on A2. Just re-handled everything and 100mm now works good on A2. I bellive the body pins on the A2 were the culprit. Thanks