failed to show Configuration>map new map

hi.
when i create new map without any background image (or with) and save it, icant configure it in configuration>maps>map name
but i can see it in monitoring>maps>map name

by inspecting element feature of google chrom of that page i 've got this information :
chrome://devtools/imgstore.php?imageid=Fatal error Call undefined function session_start() /usr/local/www/vhosts/zabbix/include/config.inc.php