Here is a great page that discusses many problems that you
might have. With only the limited info you supplied in your post, my first guess is to look at the file permissions on your test script; as Andy says, many crond implementations will not even try to run a script with permissions that it considers to be incorrect.
My second guess would be that you might need to let crond know about your change to the cron table (with -HUP).
Let us know if you need further help after trying the suggestions in the referenced webpage.