Sounds as if you may have bent or moved the small spring that controls the slide release lever, possibly during cleaning or reassembly.
The picture above showing the normal position and shape is from this thread: http://www.kahrtalk.com/showthread.p...sues-and-fixes In the thread, Greg offers several hints about things to watch out for with your Kahr. This little spring's shape, position, and tightness, as well as where the slide stop is positioned while reassembling the gun all impact the function of the slide lock and its ability to properly lock back the slide.
Best of luck, sir!
It would be so nice if something made sense for a change.
-- Alice in Lewis Carroll's Alice's Adventures in Wonderland