Originally posted by photoptimist Maybe the locking pin is stuck under the mount?
In stevebrot's image above, notice the pin between the left-center screw and seven ball-bearing electrical contacts. That is what locks the lens in place and is retracted by pushing the lens release button. Maybe that pin is out of alignment or stuck under the mount. If so, remove the mount, check the pin, and make sure you reassemble the mount ring with the pin sticking through the hole.
Good luck!
Hi,
Thanks so much for your response.
After few tries i am able to reattach properly.And i can mount my lenses with out any issues.
The reason i removed the mount was i was trying a different mount (adaptist mount) which allows me to mount not only Pentax Lenses but Nikon and Contax C/Y Mount leneses.
Thanks