Thanks a lot Ken !
By the way, like your quote in your signature

Hello James,
Thanks for your answer. But I have just purchased the flash lights, and do not want to change right now...
The problem I have is known apperently : when I link my K20D to the flash light, the flash triggers once, and then no more. I have to "reset" the flash light by presing the Test button. It seems that this issue comes from the fact that the Pentax camera "are sensitive to sync polarity. The sync cable that comes with the interfit lights is center positive".
One way to solve the issue is to buy (from Interfit of course...) an infra red trigge. It seems to be working fine, since the Sync connector is not use in this case.
But I would prefer to use a radio trigger. My question is: does it work, because the radio trigger on the camera has to be plugged in the Sync connector.... so, will it work or have the same problem than with the cable ?!
If anyone is using this settup, or has had a problem with that, I would be pleased to know !
Thanks
Matdust

Hello,
I have this problem with my K20D and the EX150 Interfit flash lights...
Because I want to ba able to take several shots one after another, the solution you give here will not be efficient for me.
Interfit recommands to use the INT411 infrared transmitter. Why not the INT412 radio transmitter ? Is anyone using Interfit EX150 flash lights with INT412 raio Tx ? Can you tell me if it works or if it has the same issue than with the synch cable ?!
Thanks a lot,
Matdust