Apache Configuration - DNS

Hello, sorry to bother you all. I hope you guys can help me out on this one. So when I type in www.transportesantamaria.com.mx it goes directly to the page but when dropping off the www and just like http://transportesantamaria.com.mx It takes me to the folder directory. I have no .htaccess configured and my DNS configuration looks like this:

$TTL	1800
@		IN	SOA	NS1.DIGITALOCEAN.COM.	hostmaster.transportesantamaria.com.mx. (
			1413392660 ; last update: 2014-10-15 17:04:20 UTC
			3600 ; refresh
			900 ; retry
			1209600 ; expire
			1800 ; ttl
			)
             IN      NS      NS1.DIGITALOCEAN.COM.
                     NS      NS2.DIGITALOCEAN.COM.
                     NS      NS3.DIGITALOCEAN.COM.
			MX 1	ASPMX.L.GOOGLE.COM.
			MX 5	ALT1.ASPMX.L.GOOGLE.COM.
			MX 5	ALT2.ASPMX.L.GOOGLE.COM.
			MX 10	ASPMX2.GOOGLEMAIL.COM.
			MX 10	ASPMX3.GOOGLEMAIL.COM.
@	IN A	104.131.0.155
www	CNAME	@
*	CNAME	@

Also here is the .conf file

<VirtualHost *:80>
        # The ServerName directive sets the request scheme, hostname and port th                                                                             at
        # the server uses to identify itself. This is used when creating
        # redirection URLs. In the context of virtual hosts, the ServerName
        # specifies what hostname must appear in the request's Host: header to
        # match this virtual host. For the default virtual host (this file) this
        # value is not decisive as it is used as a last resort host regardless.
        # However, you must set it for any further virtual host explicitly.

        ServerName transportesantamaria.com.mx
        ServerAlias www.transportesantamaria.com.mx
        ServerAdmin servicios@transportesantamaria.com.mx
        DocumentRoot /var/www/transportesantamaria.com.mx/public_html
.....

Thanks in advance