Have you made your people a real team bound by a genuine sense of "we"? If not, ask yourself — and your group members — these questions to understand what more you must do:
Are we mutually committed to a compelling and worthwhile purpose? Do we know not just which task we must perform, but who will benefit from our work? Do we believe that if we disappeared today, the world would be different tomorrow?
Are we pursuing clear goals based on that purpose, and do we have plans in place for reaching them?
Does everyone know how the team does its work? Does everyone understand their roles and responsibilities? Are work processes clear? Do we share a set of values and beliefs about what we expect of each other and how we treat each other? Does everyone know how we're doing, both as a group and individually?