Much of what I do is help clients out with performance accountability issues.  A client will pose a scenario to me that involves an employee who has consistently underperformed.  If you have an employee who is underperforming, ask yourself these questions:

1. Does the employee know what they are supposed to do?
2. Have they been trained on how to do the work?
3. Do they have the skill and abilities to do what you hired them to do?
4. Do they know that their performance doesn't meet standards set?
5. Do they WANT to do the job?
6. Do they have the tools to do their job?
7. Is something negative happening to them when they actually do what you are asking them to do?  For instance:  You have a receptionist who is supposed to do an overhead page for a sales person when a customer is present.  Whenever the receptionist pages overhead she gets an earful from salespeople.
8. Is something positive happening when they are doing something they aren't supposed to do?  For instance, if you manage sales people and give them a commission for a sale they made to another salesperson's client, don't expect that behavior to stop soon.
9. Are there barriers to performance beyond the employees control (i.e. no raw products to manufacture, etc)