Nagios 2.7 and pluggins in libxece?



I installed nagios 2.7 and pluggins from scratch.
I have configure apache2 as found in docus
ScriptAlias /nagios/cgi-bin /usr/local/nagios/sbin

The problem is now that all pluggins in libexec ar not found.
If I configure
ScriptAlias /nagios/cgi-bin /usr/local/nagios/libexec

The other ones are not found.
What is wrong?
Do I have to move all pluggins from libexec to sbin?
I don’t think so, why nagios pluggins would then install there?
What is the clue?