"Working in a team is not always something easy" is the understatement of the year. In my work with teams as a teamwork expert and coach I find that real collaboration is rare. The best we often can hope for is cooperation, but what I most often see is actually what 3 year old kids do before they learn to share, it is called Side-By-side-play. This is, I won't mess with your stuff, you won't mess with mine and we will call it collaboration. Saying, "I want my independent sales staff to collaborate now." Is like saying, "My kid knows how to crawl, now it is time to run." Learning and growth just don't happen that way.
Another analogy, think of a relay team vs. a soccer team. When I have the baton in a relay, I am the only one running, when we trade the baton we are cooperating. A soccer team on the other hand, is constantly collaborating, people play multiple roles, what ever is needed at the time, and even if I am not the one with the ball, I am still in the game blocking, positioning, or defending.
Collaboration requires intentional interdependence. Leaders must organize their teams to need each other in every step of the sales process. In sales if you and I are collaborating, I cannot close a sale without you. I need you at every step of the sale.
At least to begin with, I suggest that you don't strive for collaboration. First strive to get cooperation. This is very simply sharing in the process of making the sale. One person can still close the sale by themselves at this point but we each have a defined part to play, those parts don't necessarily require us to work together but they do require us to coordinate our efforts. Coordination can make a powerful jump in productivity and success. Coordination looks like two people working together, passing the ball back and forth, looking out for each other.