Reference numbers may not appear in form 1278 when linked to form 1269 because the materials have already been issued to vehicles. Once materials are issued, they cannot be searched or selected for a return in the Goods Return GST (1278) form.

To resolve this, only materials that have not yet been issued can be used for generating reference numbers in form 1278. Ensure that the items intended for return are still available and not yet allocated to any vehicle.