Hi all, the limit of number of events is VVF is the following: In the chi2 fit functions the sum of MC events need to be above 0 and the number of data events need to be above 0. Cheers, Wolfgang ----------------------------------------------------------------------------- Wolfgang Menges Queen Mary, University of London SLAC, MS 35 Mile End Road 2575 Sand Hill Road London, E1 4NS, UK Menlo Park, CA 94025, USA ++44 20 7882 3753 ++1 650 926 8503 [log in to unmask] -----------------------------------------------------------------------------