Can you help me to solve this problem
Before end of example you have to put number of cycles
say, …/rfluka -N0 -M5 example
starting cycle from 0 to 5 means total 5 cycles
…/rfluka -N5 -M7 example
starting cycle from 5th to 7th means additional 2 cycles
it seems that you are not using the latest version of FLUKA. Please install FLUKA 4-0.0 from https://fluka.cern/download/latest-fluka-release
Also try to run your simulations in a separate directory, not where FLUKA is installed.