First create DNS entries for each subdomain in the parent domain DNS record. Next use Apache's virtual host feature to configure the subdomains on the each VPS.

The server ignoring it almost likely means you screwed up the configuration, some how. Apache is appallingly poor at telling you when screwed your configuration up. Of course, we're appalling poor ...

This simple example demonstrates how to get virtual hosts up and running quickly on your WAMP server.