crontab does not work, but I do not see any trouble with this

Hello.
I have inserted a few entries to the crontab using "sudo crontab -e" and vim editor. My crontab looks like below:
---------------------------------------------------------------
# m h dom mon dow command
5 11 * * * /home/gaali/db_backup.sh
~
~
~
--------------------------------------------------------------

db_backup.sh looks like below:
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dest="$HOME"
day=$(date '+%y%m%d_%H%M')
name="gaali"
archive_file="$day.tar"

echo "Backing $name > $dest/$name$archive_file up ..."

pg_dump -U postgres -Ft -b $name > $dest/$name$archive_file

echo "... Backup finished"
-------------------------------------------------------------

When I run "sudo /home/gaali/db_backup.sh" then it works fine. But it requires postgreSQL password.

Does my shell command requiring password cause the crontab failure?

Please help me!!!
Any suggestion would be highly appreciated!

... Orgil