Cron As Postgres User Not Working

I was hoping someone could shed some light on a cron related issue I'm having.

I've been using linux for a while...but never really used crons.

My cron is supposed to dump a postgres db in tar.gz format every minute (for testing purposes) but it doesn't.

I opened my cron in vim via:

Code:
postgres@myhost:~$ crontab -e
And here's the cron:

Code:
* * * * * /usr/bin/pg_dump -D warranty_1_6_test | gzip -c > /var/www/test/postgres/backup$(date +"%Y%m%d_%H%M").tar.gz

Also:

Code:
postgres@myhost:~$ ls -lah /var/www/test/postgres/
total 8.0K
drwxrwxrwx 2 postgres postgres 4.0K 2007-06-14 12:01 .
drwxr-xr-x 3 user user 4.0K 2007-06-14 11:47 ..

Running the backup command via CLI works fine.