In many work situations, one employee with one chip on the shoulder can easily chip away at the morale and satisfaction of his or her co-workers. There is even a contagious aspect to this, as scowls can easily spread from one employee to another.
One approach is to meet with the scowling employee again, but rather than talking about attitude, talk about behavior. And, instead of saying what is bothering you, ask what is bothering him. If his behavior is interfering with teamwork and productivity, he should be so advised, and should be informed of the possible consequences associated with such behavior.
It may also be helpful to spend more time observing what is going on in the department. Is it possible that the employees are engaging in some sort of behavior that is putting a scowl on this individual's face? A related step is to consider holding more departmental meetings to review objectives and build consensus and teamwork.
It is also possible that you have a bright and creative individual who works best alone. In this age of building jobs around people's strengths, it is important to review this employee's job in addition to reviewing him.
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