Cron cleared after every 5 days

Hi

I have created a cron job which executes every 3 mins. its working fine after starting for 5 days than it automatically got stopped. when I checked crontab it was blank.

my crontab is like below

*/3 * * * * /home/test.sh

It is working continuous 5 days and that got stopped automatically and line which I have added in crontab
"*/3 * * * * /home/test.sh" is not there.

there is no error in cron logs too.

Please suggest/guide me what should I do?

Thanks.