jQuery Grid Plugin - jqGrid

Hi I've got jqGrid which works flawlessly normally however when I turn on grouping I get no results at all.

My setup:

- I use the xmlmap param for columns in the colModel and XML remote data

- I use repeatitems: false

- I have the latest jQuery 1.4.2 and jqGrid 3.8

I get no error in FireBug and no output although when I look at the request I'm getting XML as usual

My config is as follows:

$("#jqgrid-container-SwqkdBwfXg").jqGrid(
{
  "url":"/a-valid-url",
  "datatype":"xml",
  "mtype":"POST",
  "height":"600",
  "caption":"",
  "colNames":["KeyCriteria","Title","Description","Owner","Updated At","Created At","Actions"],
  "colModel":
  [
    {
      "name":"KeyCriteria",
      "index":"KeyCriteria",
      "xmlmap":"keycriteria",
      "sortable":true,
      "hidden":false,
      "width":255,
      "title":true,
      "resizable":true
    },
    {
      "name":"title",
      "index":"title",
      "xmlmap":"title",
      "sortable":true,
      "hidden":false,
      "width":340,
      "title":true,
      "resizable":true
    },
    {"name":"description","index":"description","xmlmap":"description","sortable":true,"hidden":false,"width":680,"title":true,"resizable":true},
    {"name":"Creator","index":"Creator","xmlmap":"creator","sortable":true,"hidden":false,"width":93,"title":true,"resizable":true},
    {"name":"updated_at","index":"updated_at","xmlmap":"updated_at","sortable":true,"hidden":false,"width":68,"title":true,"resizable":true},
    {"name":"created_at","index":"created_at","xmlmap":"created_at","sortable":true,"hidden":false,"width":68,"title":true,"resizable":true},
    {"name":"Actions","sortable":false,"width":45,"xmlmap":"actions"}
  ],
  "rownumbers":true,
  "multiselect":true,
  "pager":"jqgrid-container-SwqkdBwfXg-pager",
  "rowNum":50,
  "rowList":[10,25,50,100,500,1000],
  "viewrecords":true,
  "sortname":"id",
  "sortorder":"asc",
  "sortable":true,
  "gridview":true,
  "viewsortcols":[true,"horizontal",true],
  "grouping":true,
  "groupingView":{"groupDataSorted":true,"groupField":["KeyCriteria"]},
  "xmlReader":{"repeatitems":false},
});