I'm puzzled by this one. I hope you can explain it to me.
I have a ksh shell script that gzips a file among other things. This works perfectly fine when the script is manually run through a shell. However, when the same script is run through cron, it does everything correctly, but it will not gzip! Is there something basic I'm overlooking?
Can you post the crontab entry, the script (or the portion that deals with the gzip)?
First thing I would look for is that the gzip command is in your path (you don't say it starts and errors so one has to assume it does not run) when a script is run in cron. Are you getting output from the cron? Can you add a line to show the PATH variable (echo $PATH or env)?