Reading some of the
reviews of this flash, it seems to have a checkered record of operation with various Pentax cameras. I don't have one, but it does sound like it should work in manual mode without any fancy settings enabled/disabled. But do check your flash mode on both the flash and camera, then see if there is any flash discharge from the hotshoe you can get it to do, whether or not it registers in the exposure. One of the reviewers of the flash indicated a similar experience to yours - hopefully it can be worked out for you...