Sorting and filtering not working

[ITA]

Hi

i use a kendoGrid to provide data in my .net webfrontend. The data is shown correct, but sorting and filtering is nor working. But why?

<script>
                $(document).ready(function () {
                    $("#grid").kendoGrid({
                        dataSource: {
                            type: "json",
                            transport: {
                                read: "fabico1.json"
                            },
                            schema: {
                                model: {
                                    fields: {
                                        Artikel: { type: "string" },
                                        Bez: { type: "string" },
                                        Menge: { type: "number" },
                                        Einh: {type: "string"}
                                    }
                                }
                            },
                            pageSize: 30,
                            serverPaging: true,
                            serverFiltering: true,
                            serverSorting: true
                        },
                        height: 430,
                        filterable: true,
                        sortable: true,
                        pageable: true,
                        columns: [{
                            field: "Artikel",
                            width: 150,
                            filterable: true
                        },
                            {
                                field: "Bez",
                            },
                        {
                            field: "Menge"
                            },
                        {
                            field: "Einh",
                            width: 150
                        }
                        ]
                    });
                });
            </script>