Have you got PT-04s?
If the answer is yes I might be able to help, if it's no then here are some general things to check.
1) does the check light on the trigger illuminate briefly when you press the test button? Does the light come on when you release the shutter?
2) does the corresponding check light come on on the receiver when you test fire the trigger or release the shutter?
If the answer is no, try leaving the setting on the trigger to 1.1 and change the receiver channels to 1.2, 2.1, and 2.1 and see if anything happens. The first set of PT-04 trigger/receivers I had worked only when they were set on different channels (not the world's best quality control).
If the answer is yes, try setting the camera to manual and selecting a shutter speed lower than the camera flash sync. PT-04s don't sync reliably above 1/125 sec. The other possibility is that they simply won't trigger the strobe. My original PT-04s would not trigger my Pentax AF400FTZ strobe, but worked with my old Cobra strobes.
Lastly, I recently bought some tougher PT-04s with a much better build quality. They work every single time without fail, so far up to 50 metres range; the trigger has a much better internal aerial and the receivers are powered by AAA batteries with metal stand fixings.