Tokina canon eos 350D error 99 - Tokina AT-X 124 PRO DX Lens for Canon

Are you trying to waste people's time here, or what?
Rokinon lens, Nikon mount, then mixing that with a Canon EOS 350D???

Err 99 could mean several different things, such as... Memory Card
Lens
Lens contacts....

A few things you can try.
Remove the memory card an enable "shooting with out memory card" and see if you still get the error. If it works your memory card may be bad.
Try another lens if you can
Clean the lens contacts with a pencil eraser (be careful not to get eraser dust in the camera body or in the lens)
I have heard Canon recommend upgrading the camera's firmware (go to Canon's website todownloadthe latest firmware and follow Canon's instructions for the upgrade).
I saved the worst for last, Err 99 could be related to the shutter failing which would mean a trip to Canon for repair.
Good Luck

Hello hemantp. This error code in this model indicates that the lens electrical contacts are dirty or slightly oxidized. To clean them you will need a common pencil with a clean eraser on the end and a lens cloth.

Detach the lens from the camera and hold it so that the lens' gold contacts are pointing down. Lightly "erase" their exposed surfaces and then clean them with the lens cloth to remove any debris.

Do the same with the gold contacts inside the camera body. Although this is a wee bit more challenging, you can do it by holding the camera so that the lens opening points down. That way no debris will fall inside as you clean. Joe

If you get err99 with lens then lens diapharm unit goes wrong and its giving er99.
if you getting with body and there is coupleof possiblities.

please descride brifly your camera fault
how and when you geting err99

It is most likely an electrical contact failure between the lens and the camera. For more details and possible causes read the following article:
http://www.lensrentals.com/news/2008.12.31/canon-err99

Have you been to the support section of Canon's website to find out what "error 99" means?

I think I answered this earlier did you ask this question more tan once?

well here you are a simple fix from experience.

The guy at Canon tech support listened to my woes and then told me that the lens contacts were dirty and to get a pencil with an eraser on the end, just a regular old pencil with a red rubber eraser. Detach the lens from the camera, hold it so that the lens’ gold contacts are pointing down and lightly erase their exposed surface, cleaning them of any hand oil that might have gotten on them. Do the same thing with the gold contacts inside the camera body. This is a bit harder but it’s doable: just hold camera so lens opening points down so no gunk falls in. Erase lightly. I used a lens cloth and dabbed at the contacts rather than blow them so as not to blow the erasings inside the camera.
I did this to each of my three lenses just to be sure. Lo and behold, it worked (so far anyway). I’ve shot numerous pictures with each lens and have not gotten a single error 99 message.

Please rate this help to keep the service online

err 99 is moisture or dew inside the camera.

Error 99 is a "catch all" error that has several causes. It could be that your battery is not fully charged, especially if it is a generic, non-Canon battery. Charge for at least over night even if the charger says it's full. If that's not the cause, switches inside the camera will have to be cleaned by a repair shop.

Try this:
http://www.richardsnotes.org/archives/2005/04/29/50mm-lens-contact-points/