Apache Multiple Sub Domains With One IP Address

Sounds like you need to add NameVirtualHost directive to your configuration.

NameVirtualHost         *:80

Under some circumstances Apache may not be able to handle *:80 VirtualHosts correctly. In those cases you should map VirtualHosts directly on specific IPs.

NameVirtualHost         8.8.8.8:80<VirtualHost 8.8.8.8:80>    ServerName  staging.mydomain.com    ServerAlias stage.mydomain.com    DocumentRoot /var/www/html/mydomain.com/staging/</VirtualHost><VirtualHost 8.8.8.8:80>    ServerName  dev.mydomain.com    ServerAlias development.mydomain.com    DocumentRoot /var/www/html/mydomain.com/dev/</VirtualHost>

You can also run apachectl -t -D DUMP_VHOSTS to see how Apache parses the VirtualHost configuration.

Update: As mentioned in the comments, usually you can just use NameVirtualHost *:80. So most of the time you can configure the virtual hosts as follows.

NameVirtualHost         *:80<VirtualHost *:80>    ServerName  staging.mydomain.com    ServerAlias stage.mydomain.com    DocumentRoot /var/www/html/mydomain.com/staging/</VirtualHost><VirtualHost *:80>    ServerName  dev.mydomain.com    ServerAlias development.mydomain.com    DocumentRoot /var/www/html/mydomain.com/dev/</VirtualHost>