Fetch mail by cron problem

Hello!
I have problem that I can't understand why.
I have crontab:
*/1 * * * * root /usr/bin/php "/var/www/html/helpdesk/api/cron.php"
It looks like it working without any errors because cron and system logs doesn't contain any errors, just this:
Jan 13 23:22:01 sd CRON[22622]: (root) CMD (root /usr/bin/php "/var/www/html/helpdesk/api/cron.php")
It means that cron run this job but no mail is fetched.
if I run /usr/bin/php "/var/www/html/helpdesk/api/cron.php from command line then mail is fetching without problem and processed by osTicket
Could you help me to understand and resolve problem why mail is not fetching by cron?