problems running cron jobs

hi.

i'm trying to setup a cron job to run a php script. for testing i made a job to run the script every 5 minutes, but it isn't running at all, ever.

i used the "crontab -e" command as root to edit my crontab and added this line (name of actual script edited out)

*/5 * * * * /usr/bin/script

i run this script manually all the time and it works perfectly.

am i missing something?