SuExec doesn't work on PHP as Module. This setting works only for CGI applications. PHP as CGI for example. Apache-mpm-itk will help you.
For FreeBSD:
Code:
# cd /usr/ports/www/apache22
# echo "WITH_MPM=ITK" > Makefile.local
# make config (disable IPv6, enable mod_suexec)
# make
# make deinstall reinstall
Also you need to add "Option ApacheMPM" to the ispmanager config (/usdr/local/ispmgr/etc/ispmgr.conf) and restart panel (killall ispmgr)
Next for all early created sites you need to change SuexecUserGroup on AssignUserID and restart apache.