Know Your Own Weaknesses
They either won't admit to them or they don't have a firm understanding of what it takes to be a good manager and, therefore, can't assess the gap between their behavior and that required to be an effective manager. By not recognizing weaknesses, a manager sets employees up for ineffective and unproductive output and behavior. A manager must be able to objectively evaluate what he/she does well and doesn't do as well. Once identified it is critical that they work hard to change their behavior to more closely align with the traits and skills necessary to effectively manage. Common Attributes of Good Managers points out the basic requirements of effective management. Compare your behavior and tendencies against the list in that article and objectively rate you in terms of any gaps that might exist. Use those gaps to work on changing your work behavior to become more effective.