Delete it. Re-enter it and follow the interview carefully. If you still have problems, reply being more specific about the "errors".
Go through the entire education interview until you reach a screen titled "Your Education Expenses Summary". Click delete next to the student's name. You'll then get the "Your Education Expenses Summary" screen again. Click the "Add a student" button.
If the student is your dependent, he must have been previously entered as your dependent, in the personal info section.