Check in Education Edge to make sure the current semester has started:

1. Go to Configuration > Academic Years
2. Double click the current academic year, at the school in question that the class page is linked to
3. In the "Session" section at the bottom double click the applicable session
4. Click the "Terms" tab, check the start date of the current term

If the term hasn't yet started, then the class list on the class page in OCC does not populate.

If you would like the class pages to list the class before the start of the term, you can suggest this at our Idea Bank, found here: http://bbncfeedback.blackbaud.com/forums/905-general