Why my MathWorks account do not valid to make activation for DVD R2013 with serial number ,?

After installing of my DVD MATLAB, a step for complete activation is to enter serial number and e-mail, when I enter my email a message "The e-mail address you entered is associated with a non-student MathWorks account " "Either create a new account by providing a different e-mail address"

So, what I must do to complete activation taking into account I have a valid serial number??