Individual Column Searching (Not Working)

Help me to resolve this problem. Individual Column Search not work for me

var table = $("#table_unit").DataTable({

            processing: true,
            serverSide: true,
            ajax: {"url": "dataunit/get_data_json", "type": "POST"},
            columns: [
                  {"data": "unit_id"},
                  {"data": "unit_nama"},
                  {"data": "unit_kode"},
                  {"data": "unit_induk"},
                  {"data": "aksi"},
                  //{"data": "aksi"}
            ],
            order: [[1, 'asc']],
            //language: {"url": "//cdn.datatables.net/plug-ins/1.10.19/i18n/Indonesian.json"},
            //Penomoran Baris
            columnDefs: 
            [
            {
                targets : 0,
                orderable : false,
                render : function (data, type, row, meta) {
                    return meta.row + meta.settings._iDisplayStart + 1;
                }
            },
            {
                targets : 4,
                orderable : false,
            }
            ],

            dom: '<"datatable-header"flB><"datatable-scroll-wrap"t><"datatable-footer"ip>',
            buttons: {            
                dom: {
                    button: {
                        className: 'btn btn-light'
                    }
                },
                buttons: [
                    'copyHtml5',
                    'excelHtml5',
                    'csvHtml5',
                    'pdfHtml5',
                    {
                        extend: 'print',
                        text: '<i class="icon-printer mr-2"></i> Print table',
                        className: 'btn btn-light'
                    }
                ]
            },
            initComplete: function () {
                this.api().columns().every(function() {
                    var column = this;
                    var select = $('<select class="form-control filter-select" data-placeholder="Filter"><option value=""></option></select>')
                        .appendTo($(column.footer()).not(':last-child').empty())
                        .on('change', function() {
                            var val = $.fn.dataTable.util.escapeRegex(
                                $(this).val()
                            );
     
                            column
                                .search( val ? '^'+val+'$' : '', true, false )
                                .draw();
                        });
     
                    column.data().unique().sort().each(function (d, j) {
                        select.append('<option value="'+d.replace(/<(?:.|\n)*?>/gm, '')+'">'+d.replace(/<(?:.|\n)*?>/gm, '')+'</option>')
                    });
                });
            }
        });