Pentax K10D won't work with lens from Pentax K100 (film0

What happens when you try to change the exposure mode by turning the exposure dial? Try setting it to the green AUTO mode. Any change?

Only Pentax DA and FA J lenses and D FA/FA/F/A lenses having an "A" position on the aperture ring can be used with this camera.

The lens you have is HSM DG

Any Pentax K-mount lens will fit any Pentax DSLR. The DSLR will fire the shutter.  There is a menu setting (RTFM) which allows the use of older lenses, but you will lose some of the automation (again RTFM). Remember to allow that the effective focal length when using a "film" lens on a DSLR body goes up by 50%.
A standard 50mm lens becomes a 75mm equivalent, but stays a large aperture.

Pentax K10D shutter release won't function, mirror doesn't open, all else normal.

Clean the contacts on the camera body and the lens where they connect with a cotton swab lightly dampened with rubbing alcohol.

If u used to have a Pentax camera, i would recommend you buying a Pentax DSLR, because Pentax film lenses still works on Pentax DSLR. I still use some of my prime lenses on my K10D.

Might be temporary lack of communication between lens and body - try cleaning the contacts on both gently with a lint-free cloth and a very little IPA.

Hello,

I don't own a K10D, but I do own a K100D which I have successfully used both manual focus & auto-focus lenses from my old Pentax stash!

1) If it is a manual focus lens, you need to turn off Autofocus on the body of your K10D. On my K100D, there is a switch on the side of the lens mount that says [-MF or -AF]. "-MF" is manual focus mode & "-AF" is autofocus mode. Since your lens doesn't have autofocus capability, turn it to the "-MF" mode.

Also . . . When I press "Menu" and go to "Custom Setting", I change two settings . . .

1) I change "Using aperture ring" to "Permitted". This allows you to use manual lenses (M lenses) that do not have an auto(exposure) setting, and also lets you use Auto lenses (A, KA, KA2, FA, etc.) in either the Auto or manual aperture setting modes.

2) I change "Fl with S lens used" so that even with a manual focus lens, although I don't have autofocus capability, my K100D beeps and shows a little red square in the viewfinder when I have successfully focused manually!

The K10D should have the same options.

This should get you up and running!

I have had a load of fun with my old lens on my new digital Pentax!

Take care & Happy Imaging!
Glen
:)

throw it away, its already old, buy new ones a pentax g40, its a computer compatible.

the film might not have been catching onto the wheel it has happend to me befor