If I rename ...site/lib/DBD/CSV.pm, the script above does error out with "install_driver(CSV) failed: Can't locate DBD/CSV.pm in @INC..." as it should. If you're not getting that error message, then perhaps you have a CSV.pm somewhere else in your @INC, or else you haven't turned RaiseError on for the connect, or have some other bug in your error reporting strategy.