title: jqGrid - No such method: setFrozenColumns
body: <p>I'm using jqgrid 4.1.2, a sample of the code used to create the grid is shown below. Everything works fine until I try to set frozen columns at which point a runtime error is thrown - ' jqGrid - No such method: setFrozenColumns ' - can anyone see why this is happening ?</p>
  
  <pre><code>jQuery("#grid").jqGrid({
      url: '@Url.Action("LoadGrid")',
      editurl: '@Url.Action("UpdateGrid")',
      datatype: 'json',
      shrinkToFit: false,
      autowidth: true,
      mtype: 'POST',
      ..... columns ....
      rowNum: 100,
      rowList: [5, 10, 20, 50],
      sortname: 'Id',
      sortorder: "desc",
      viewrecords: true,
      caption: 'Instances',
      height: 225
  });
  $("#grid").navGrid("#pager", { edit: true, add: false, del: false, search: false });
  $("#grid").jqGrid('setFrozenColumns');
  </code></pre>