Configure Apache .conf for Alias

So I cant get an alias working in "/etc/httpd/conf.d/vhosts.conf" which contains all of my virtual hosts:

<VirtualHost *> 
    ServerName example.com
    Alias /ncn /var/www/html/ncn
    DocumentRoot /var/www/html/mjp
</VirtualHost>

I want my alias to work so I can point example.com/ncn to "/var/www/html/ncn".

This works if I have it in "/etc/httpd/conf/httpd.conf" but not my "/etc/httpd/conf.d/vhosts.conf"

Any ideas why? Everything else seems to work i.e. ServerAlias's

Cheers, Peter

<VirtualHost *> 
    ServerName example.com
    DocumentRoot /var/www/html/mjp

    Alias /ncn "/var/www/html/ncn"

    <Directory "/var/www/html/ncn">
        Options None
        AllowOverride None
        Order allow,deny
        Allow from all
    </Directory>
</VirtualHost>

Source: https://stackoverflow.com