Pentax istD digital SLR

[fotolode]

Hello everyone, I got this particular camera and it says
that all K mounts are compatible with this digital slr.

I purchased a zoom lens (manual focus) and it does not
work. Of course, it's a K mount. When I screw in the lens,
I get Av flashing and it will not take pictures.

Does anyone have this similar problem? I'm afraid of purchasing
another lens only to replicate this same problem.

Thank You

 

[hobbes28]

If it has an apeture ring on it, it must be set on the f22 or f32 whichever it has (it will be the number in the different color) for the camera to be able and automatically adjust the apeture.