you also need permissions to whatever the script is calling - if your user can't run gzip, your script probably won't be able to (security issue).

however, if you can't solve it from this point, it would be helpful to show us the script as well as: mkdir test; cd test; echo "" > testfile; umask; ls -l; ls -ld $PWD

and show us the permissions on the script and whatever modules or programs the script uses (start with the permissions on perl itself if you can't run any perl as that user).