Think about every member of your staff and ask yourself this question: If he/she wasn't already working for me, would I hire him/her?
If the answer is yes, you did an excellent job hiring, empowering, and maintaining that person as an asset. If the answer is no, you're maintaining a liability.
If you find you're maintaining liabilities you have three choices. 1) turn her into an asset; 2) terminate the liability; 3) let the liability continue to be a drag on your spirit, your department and your team.
The first option should exhaust you, the second should sadden you, and the third should embarrass you.