Item Fulfilment Serial Numbers

I'm trying to list all the serial numbers that have been allocated on an item fulfilment. I'm trying to do this on an aftersubmit event as below.

define(['N/record','N/search'],

    function(record,search){

        function afterSubmit(context) {

            if(context.type == 'create' || context.type == 'edit'){

                var rec = context.newRecord;

                //Load saved search for serial numbers

                var serailnumbersearch = search.load({id: 'customsearch_wrsinventorynumbersforso'})

                serailnumbersearch.filters.push(['transaction.internalid','anyof', rec.id])

                var serailnumbersearch = serailnumbersearch.run()

                var serailnumbersearch = serailnumbersearch.getRange({start: 0, end: 50});

                //Loop through saved search

                for (var i = 0; i < serailnumbersearch.length; i++){

                    log.debug('Serial Number',serailnumbersearch[i].getValue('inventorynumber'));

                }

            }

        }

        return {afterSubmit: afterSubmit}