My first guess is that something is wrong with your syntax in the crontab entry, since it works ok at your command line. Double check it with crontab(5) (type 'man 5 crontab').

If it seems ok, add something in your script to debug. Printing something to stderr from a cronjob should email the output to you. Try something such as: print STDERR 'At the top of my perl cron job'; at the top, and a similar statement at the bottom.

Another way you could debug it is by printing some output to a temporary file.