I would suggest calling and talking to an instructor. This way you can go over the problem and find out what is going on. If the answer you gave was wrong they would help you understand it.
To contact an instructor by email:
Go to the Help Center tab on your student portal and click "Find Answers/ Ask a question" button. Type the word “instructor” in the search box and press enter. You will see a few articles that may answer your question (we will be adding more as time goes on) but if they don't, click the Ask a Question link that appears on the black bar near the top of the page. This will allow you to Ask A Question and the question will be directed to your instructor as long as you select the Instructional support in the drop down department box on the email page.
To contact an instructor by phone:
Call toll free at your convenience by dialing 1.888.427.1000 Monday thru Friday from 9am-6pm ET