You need to talk to your apartment's management and find out exactly how they handle these things. It is very possible that you are or were just hearing from "scams" because a sub-lease is not allowed there. I hope you spoke with the Agent who offered to help you, I sure would have appreciated that kind of help!
The way our leases are set up in order to get out of it we have to find someone to re lease the room. So i do believe that they have to sign their own lease for a year. My lease isn't suppose to end in October which is when I took over a girls lease and signed my own lease.
Sub leases are hard. What are the particulars of your lease. Monthly lease, when does it end, is there a clause in your contract that says you MAY sublet?
What was the working in your craigslist listing?
Send me a copy of your contract and I will check it out if you like.