One reason could be that the course wiki is affiliated to more than one instructor’s account. If you are co-teaching, your colleague would have to create the wiki, and add you as an additional Organizer.
If you are the only instructor affiliated with the course, and cannot create the course wiki or can't access Wikispaces@Columbia, please follow these steps:
1) Log in at this link – https://www1.columbia.edu/sec-cgi-bin/ccnmtl/access/valid-user/token.php
2) Review the resulting page and verify that your email is shown (last entry on page).
3a) If yes, email is displayed, copy the results and then paste them into an email to firstname.lastname@example.org. We will evaluate the problem and get back to you as soon as possible.
3b) If no email is shown, your email has not been activated and Wikispaces can not proceed till you do so. Visit CUIT's "Manage my UNI" page and activate your email account.