Obviously, the objective behind a business mixer is to make new contacts, but if most of the room consists of new contacts, it can be difficult to break the ice. The people who know each other tend to pair up or cluster together in impenetrable cliques and before you know it, you're standing awkwardly on the periphery wishing you had someone to talk to.
Well, chances are you're not alone. Scan the room and you will find at least one other person who is in the same unenviable position. They may look awkward. They may look lonely. But they are the most approachable person in the room, and even before you introduce yourself, you already have something in common with them.