Not all employees are created equal. Many managers make the mistake of complaining about difficult employees but not doing anything about it. If you are trying to improve the situation with a troublesome employee, it’s time to step up and be clear. Explain your expectations of them, putting them in writing and documenting the meetings you have had on the subject. Be clear that there will be consequences if things don’t change within a certain time frame. Finally, have a company policy that notes what happens if an employee isn’t up to scratch so that you can refer to it should you need to let them go.