Check all sites and ensure that you either use * or use the IP address for all sites but dont mix IP addresses and websites. Apache will then forward all traffic for sites that dont exist to the first site that it finds in alphabetical order. So if you want that mysite.com is always found first, then chnage the domain from:
mysite.com to 0000-mysite.com and add mysite.com as aliasdomain to the 0000-mysite.com website. The domain 0000-mysite.com does not have to exist in dns, it is just used to ensure that the site is found first in alphabetical order.