Ubuntu – nagios on virtualhost cgi problems

I have been moving my nagios on apaches virtualhost and adding the following configuration file

<VirtualHost *:80>
    ServerAdmin webmaster@localhost
    ServerName  nagios.example.com
    ServerAlias nagios.example.com         
    DocumentRoot /usr/local/nagios/share
    ScriptAlias /cgi-bin/nagios /usr/local/nagios/sbin
    ScriptAlias /nagios/cgi-bin /usr/local/nagios/sbin 


    # Where the stylesheets (config files) reside
    #Alias /nagios/stylesheets /usr/local/nagios/share 

    # Where the HTML pages live
    Alias /nagios  /usr/local/nagios/share

    <Directory  /usr/local/nagios/share>
        Options FollowSymLinks
        DirectoryIndex index.php
        AllowOverride AuthConfig
        Order Allow,Deny
        Allow From All

        AuthName "Nagios Access"
        AuthType Basic
        AuthUserFile /etc/nagios3/htpasswd.users
        require valid-user
    </Directory>

    </VirtualHost>

When I browse the page I'm getting the following error:
The requested URL /cgi-bin/tac.cgi was not found on this server.
Checking the scriptaliases routes everything seems to be alright. Clicking inside of a menu the cgi problem do not persist, just on page browsing.