C:\tmp\pm>perl -MData::Dumper -we"print Dumper [1..3]" # Correct Casing, NO Problems $VAR1 = [ 1, 2, 3 ]; C:\tmp\pm>perl -MdAtA::DuMpER -we1 # NO Error Msg on Win C:\tmp\pm>perl -MdAtA::DuMpER -we"print Dumper [1..3]" # BUT won't work! Name "main::Dumper" used only once: possible typo at -e line 1. print() on unopened filehandle Dumper at -e line 1. C:\tmp\pm>perl -MdAtA::DuMpER::FAKE -we1 # What we really expected ... Can't locate dAtA/DuMpER/FAKE.pm in @INC (you may need to install the dAtA::DuMpER::FAKE module) ... C:\tmp\pm>