Why do some options appear shaded in grey?

Options which are shaded in grey are currently not available. As a rule options are not available because of the product which has been selected. For example, COD parcels can\'t be delivered to neighbours, because the money for the parcel has to be handed over in person by the consignee who is specified by the shipper. Or, for example, if you have already redirected a shipment, no further changes are possible, at least until the second delivery attempt is due.