I would guess that kp_ID_Customer_Care is a field defined in the layout's table. The error message indicates that this field does not have a value and thus there is no way to create a record in the portal's table and link it to the current record on your layout's table. Try putting a copy of this field on your layout to see what is in it.
Usually, kp fields are defined as auto entered serial numbers as this is a simple, safe and reliable way to give each record in the table a unique identifier each time a new record is created in the table.
Thanks, I figured it out.