Try each of the following steps in order until the issue is resolved:

Mark the course as graded:
  1. In Records, Courses, open the course record
  2. Select the Grading tab
  3. Open the appropriate Academic Year
  4. Mark the Graded checkbox for the marking column(s) for which grades are being imported
  5. Click OK
  6. Save and close the course
If the marking column is not available on the Grading tab for that Academic Year:
  1. On the course record, select the Restrictions 2 tab
  2. Open the Academic Year
  3. Mark the checkbox for the Term which includes the Marking Column for which grades are being imported
  4. Click OK
  5. Follow the instructions in step one to mark the course as graded for the appropriate marking column
Ensure the marking column is not marked as view-only:
  1. Open In Configuration and click Academic Years
  2. Open the appropriate Academic Year and open the appropriate Session
  3. Unmark the View Only checkbox on the marking column(s) for which grades are being imported
Ensure the marking column is associated with the correct terms
  1. Open Configuration and select Registrar Setup
  2. Select Marking Columns and open the appropriate Marking Column Set
  3. Verify the correct terms are selected for the marking column