Yafaray for caustics only

I can’t get the Yafaray 3 to create JUST caustics. Does anyone know of a special remedy to this? I only get black screen.

I had this too and it can be caused by an incompatible light source. I recreated the light and positionned it at the same place and it worked.
Make sure also your materials are proper Yafaray materials.
Do you still have a black screen ?