cygwin CRON problem

I'm able to access the local files by not the NETWORK files from cygwin
CRON. However the same script runs perfectly from the cygwin shell
command line.

Here is the script:
#!/bin/ksh
set -x
if [ -f /cygdrive/d/jobs/test.sh ]
then
echo 'file found'
else
echo 'not found'
fi


Here /cygdrive/d is the local drive.
But if I change it to :
if [ -f /cygdrive/r/test.sh ]

Then it doesn't work from CRON. It says 'not found'. However from
command line it works correctly.


Also notice that I'm using personal account (and not Administrator) to
run cygwin and cron.

Any suggestion please?