I get this weird error on my mental ray window every time.

RCGI 0.3 warn 362004: no photons stored after emitting 10000 photons
RCGI 0.2 warn 362004: no photons stored after emitting 10000 photons
RCGI 0.3 error 361053: no photons stored after emitting 1000000 photons (canceling emission job)

Nee fast help pleas.