Help Running cron job

Hi,
I am using cron for first time.
I have added following lines /etc/crontab file

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39 * * * * root echo "This command is run at one min past every hour"
39 * * * * root arp -e

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I am getting follwoing error :

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crond: can't lock /var/run/crond.pid, otherpid may be 914: Resource temporarily unavailable

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I have used follwoing command to check whether Cron is running :

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[zzzzzzz root]# ps aux | grep crond
root 914 0.0 0.2 1516 604 ? S Jan04 0:00 crond


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Any clue what's going wrong?
Help appreciated.

O.K.
No error now but thing does not work.
I have added two lines to /etc/crontab file as follows :

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03 15 * * * root date
03 15 * * * root arp -e
#####

I want to run "date" and "arp -e" at command prompt. I am on Linux machine.

As doc says no need to restart crond after editing crontab file.

Crond is running.
What's going wrong? Any clue?
Help appreciated.
Thanks