Event generation problem

Hi, after addition of scintillation properties I find problem when I generate more than 50 events.
I got the warning like ,
WARNING: G4VisManager::EndOfEvent: Automatic event keeping suspended.
The number of events exceeds the maximum, 100, that may be kept by
the vis manager
But this problem disappear when I remove the optical properties like RINDEX,SCINTILLATIONYIELD etc.