Install problem: PHP Fatal error: Class 'Silex\\Application' not found

[_jmichel]

Dear all

Probably a basic problem from a beginner
I installed AgenDAV 2.2.0 according the last doc: http://agendav.readthedocs.io/en/stable/admin/installation/

I get following errors

Case 1: Error 404

/var/log/apache2/access_log :

"GET /agendav/web/public/ HTTP/1.1" 302 344 "-" "Mozilla/5.0 (X11; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0"
"GET /agendav/web/public/login HTTP/1.1" 404 970 "-" "Mozilla/5.0 (X11; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0"

Case 2: blank screen

/var/log/apache2/access_log :

"GET /agendav/web/app/app.php HTTP/1.1" 500 - "-" "Mozilla/5.0 (X11; Linux x86_64; rv:50.0) Gecko/20100101 Firefox/50.0"

agendav/web/var/log/1017-09-26.log

agendav.INFO: Matched route "calendar". {"route_parameters":{"_controller":"[object] (Closure: {})","_route":"calendar"},"request_uri":"http://localhost/agendav/web/public/"} []

/var/log/apache2/error_log

[php5:error] PHP Fatal error:  Class 'Silex\\Application' not found in /mnt/data/nous/.www/agendav/web/app/app.php on line 14

TheApache server is local and serves other websites successfully

Configuration
Linux OpenSuse 13.1
PHP

Version 5.6.1

Loaded modules:
core mod_access_compat mod_so http_core prefork mod_unixd mod_systemd mod_authz_host mod_actions mod_alias mod_authn_file mod_auth_basic mod_authz_groupfile mod_authz_user mod_autoindex mod_cgi mod_dir mod_include mod_log_config mod_mime mod_negotiation mod_setenvif mod_status mod_userdir mod_asis mod_imagemap mod_rewrite mod_php5 mod_authz_core mod_version mod_reqtimeout mod_authn_cor

Permissions

The same as other Symfony websites

Apache

/etc/apache2/vhosts.d/ip-based_vhosts.conf

<VirtualHost agendav>
 DocumentRoot ${document_root}/agendav/web/public
 ServerName agendav
 ServerAdmin xx...@xxxxx.com
 ErrorLog ${document_root}/agendav/web/var/log/apache_err_log
 CustomLog ${document_root}/agendav/web/var/log/access_log common
 <Location />
   RewriteEngine On
   RewriteCond %{REQUEST_FILENAME} !-f
   RewriteRule ^ index.php [QSA,L]
   SetEnv AGENDAV_ENVIRONMENT=dev
 </Location>
</VirtualHost>

Any guidance would be much appreciated

Jean-Michel