I was just dealing with a similar issue on the perl5-porters mailing list. On that ticket, based on the directories used on HP-UX, the perl installed at /usr/local/bin/perl was 5.005002. Since I've been working on HP-UX 11.0 for about five years that seems about right.

Please confirm the version of Perl used in your script by performing a /usr/local/bin/perl -v and let us know what you find.