Class type should be set as Not a Nursery Class or Nursery Class. This is a field on the extended tab of student profile under school information.
This can be changed in bulk using the Group Updater (Admin > Students > Group Updater) - selecting Class Type as the student attribute.
Often this will occur for Nursery classes where the class type is Not a Nursery Class. You may also wish to check all Reception students are set the correct code, if they were previously in the Nursery class, as this does not automatically update in ScholarPack.
