Errors in crontab usually happen because the commands there are executed with a very spartanic environment. Put the command 'printenv > /tmp/xyz476' into the crontab (so that it gets executed 2 minutes in the future). You should get the environment used in crontab in the file /tmp/xyz476. Compare that with the output of 'printenv' on the command line. One of the things that changed is responsible for the failure of your script
To add the missing environment variable you might just put the definition of it in front of your script (if you use bash or something similar). Example:
1 2 * * * PATH=${PATH}:/usr/local/bin sqlloader
would add /usr/local/bin to the path before executing sqlloader