Problem with crontab

i use crontab like this :
*/10 * * * * www-data /usr/bin/php5 /usr/share/nginx/www/misc/cron/archive.php – url=http://my ip address/ > /dev/null

i want to run archiving every 10 min in everyday…but i have problem…the crontab is running , i say it because i check var/log/syslog , but the database it means piwik_archive_bulb and piwik_archive_numeric table didnt update and after a while piwik page dont have any data to load…i test crontab in this way :

su www-data -c “/usr/bin/php5 /usr/share/nginx/www/misc/cron/archive.php – url=http://my ip address/”

and it works without error also the piwik_archive_bulb and piwik_archive_numeric table update right…but when i set in crontab, nothing happen , i say it again , the crontab run , but the db didnt update

could anyone help me to fix it?

record a log via > /home/test.log and then checkout what contains the log when executed from cron ?