Problem with my new Sigma 15mm macro lens

[Man In Black]

I've started to get Error 99 when I use my new EX 150mm Macro Sigma lens withthe CanonRebel camera. I hear strange sounds coming from the lens I don't know if it is just a defective lens or is more a compatibility problem. It started when I switched from Full to 0.52m-infinity position on the lens. But now I havethe error 99most of the time for any of the positions on the lens.The camera works OK with any other lens including two other Sigmas.

[Man In Black]

It looks that the lens I had was defective. The store changed it and the new one seems to be OK. I hope it was the lensand not a compatibility problem.