You can also use the command
to make sure it is running (name and location may differ for You).
There could be a lot of things...
What does Your cronjob/crontab look like?
Do You run it through the predefined script locations in /etc/cron.* or schedule it Yourself with crontab?
As what user?
Is it executable?
Does the crontab use the full filename of Your script?
Grep for CRON in var/log/messages, /var/log/syslog or ANY logfile there.
Check for working directory, check for "shebang", check for path; if You run a script start it with #!/bin/bash to have a known shell, use ' . /etc/profile ' to get a known environment, use poor mans debugging! ie, echo status to an absolute filename.
It could help if You told us more!