Subdomain Problems, google knows us but Options

[robatcts]

Hello All

We are having a very strange subdomain problem - we launched our website subdomain a while ago and have been crawled a couple of times since then. Yesterday we sat at my boss's computer and did a few searches among other things to try and get at least the subdomain to show up - at least on the first 3 pages of Google. We tried a specific search using a phrase only found on the subdomain. The result(s) that only showed up were the domain/main site - even though the search criteria was specific to one page only found on the subdomain- I think Im getting to a question.. my bosses are worried about- that- we made a wrong decision about going with a subdomain for this modality - instead of a totally separate domain.. My question is - I guess- how do I make this subdomain a domain unto itself -how can I make sure search criteria.. say , healthcare jobs, only brings up our healthcare subdomain and not our main site with health care related material?

Thanks
Rob