A common issue is the confusion of certain letters and numbers. Notably "I," "l," and "1."

  • Capital I as in India.
  • Lowercase l as in leopard. We do not use this letter in our codes.
  • The number 1. We do not use this number in our codes.


Another reason may be that you have a used textbook and the code is no longer valid. You may also purchase course access only


For access codes inside printed textbooks, when contacting support, please provide the access code you tried entering by copying and pasting, along with a picture of the code from your book.