How to I control a different team in NBA 2k11 Association Mode?

In my settings for nba 2k11 association, I chose 4 players as the number of players playing. For some reason, I only control one team. How do I control another team? For example, the 4 teams I chose were cavs, heat, mavericks, and the celtics. I want to trade someone on the heat to the magic, but It only lets me trade the cavs. Help!|||juss getti answer poits