monitoring web - graph values not displayed for regular user

we are monitoring web services via standard zabbix built-in procedure (Monitoring -> Web). everything is fine except that regular user can not see values from the graph (response time for example). graph is displayed but when you click on Values, blank page is displayed. when i give this regular user super admin rights, it's ok.

http://www.zabbix.com/forum/showthread.php?p=92960#post92960