Slider door key lock

Take a look at our 82-306, I think this could be a simple solution.

Hmm... I'm not sure why you're having this problem. You said you reinstalled the cylinder and tried turning the key tail in different positions, which is usually the first step we recommend, so you're already ahead of the take. I have one other idea, though. Take a look at your current mortise lock and note the position spindle hole. Key in the 82-306 is meant to work in mortise locks that have a 45 degree slot to accept the tail. Is yours also 45 degrees? If so, then I don't know what else would be causing problems. You might need to try a locksmith to see if they can offer any insight. It may require hands-on experimentation.