error in Cron

I am working on a proxy server log and am trying to get our server to rotate the log each night and append a date to the newly rotated file. The command I am using works when run manually, but cron won't run it.
The command being run is:
/usr/local/squid/bin/squid -k rotate:harpo=$(date +%d%m%Y);mv /usr/local/squid/logs/access.log.0 /usr/local/squid/logs/access.$harpo

Cron is E-Mailing root with the message of:
/bin/sh: unexpected EOF while looking for ')'
/bin/sh: -c: line 2: syntax error

Does anyone have any idea why this command runs when bashed but won't run once the time is added and run in Cron?

Thanks

-Keith Kippen
District Technology Specialist
Morgan School District
Morgan, UT
kippenk@morgan.k12.ut.us
http://www.morgan.k12.ut.us
                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               
Received on Wed Jan 26 2000 - 08:47:36 MST