Error loading class in a hiera setup

[jehane]

I'm using puppet 5.5 with hiera.

When I'm trying to activate httpd in nagios module, puppet raised the following error :
Error: Could not retrieve catalog from remote server: Error 500 on SERVER: Server Error: Evaluation Error: Error while evaluating a Resource Statement, Could not find declared class ::apache_httpd (file: /etc/puppetlabs/code/modules/nagios/manifests/server.pp, line: 234, column: 5) on node puppetclient.domain.tld

I suppose this is a autoloading issue but I haven't find a way to correct it.

Can you fix this or indicate a work-around ?