I've got the following in my crontab

0 6 * * * user /home/user/quarter.v2
0 12 * * * user /home/user/quarter.v2
0 18 * * * user /home/user/quarter.v2
0 0 * * * user /home/user/quarter.v2

quarter.v2 is a script. I can run it manually. I want it to run four times
a day, at 6am, noon, 6pm, and midnight. But the script isn't being run.
I've had the crontab entries for two days, and the script hasn't been run
once. Have I misunderstood the way cron works?