|Before working on changing this employee's attitude, it may be helpful to work on the feedback you give her. This is one of your top salespeople, and she has not risen to her level of success by joyously accepting every piece of criticism thrown at her. In fact, if she were overly receptive to such feedback, she may well have a problem handling customer objections and closing sales.|
For feedback to be effective, it should be given as close to the problematic behavior as possible, and it should be based on the behavior itself. When people sense they are being labeled, such as by being told they have a negative attitude, they will tend to reject it.
Although you are interested in having her be more of a team player, look at the incentives and disincentives associated with this expectation. For example, if your commissions are based solely on individual performance, there is less reason for her to reach out to her teammates. If you want more team oriented actions, try implementing incentives that reward the entire team.
And finally, try to think of feedback as coaching rather than disciplining. This means less focus on negative issues, and more focus on developmental issues.