virtual host weird problem..

[paragasu <paragasu@gmail.com>]

i have problem.
i setup the dns server like this for example
A record is example.com
CNAME www.example.com point to example.com

the problem is, it works fine if i type example.com in the url.
but if i use the domain www.example.com, it point to another site on the server.
do anyone have idea what happening...

<VirtualHost example.com>
    ServerName example.com
    DocumentRoot /var/www/example
    ServerAdmin example@example.com
    ErrorLog /var/log/apache2/example-error_log
    CustomLog /var/log/apache2/example-access_log common
</VirtualHost>


thank you