STUDIO FLASH AND PENTAX DS Problem

I just bought my Pentax *ix DS and have used it with the Norman studio flash system attached, connected by a hotshoe PC adapter mounted on top of the hotshoe, for two shoots with no problem. But last weekend, all of the sudden, it failed. The camera won't trigger the Norman studio flash but would trigger a regular Vivitar flash connected by the hotshoe adapter. What seems to be the problem, and how could I fix this?

first try a new hotshoe adapter then new cables.