jQuery Grid Plugin - jqGrid

Hi,

I am using the tree facility + adjacency model + json + ASP.NET MVC more or less successfully but the nodes are all expanded after the grid is loaded. The nodes also only collaps after the second click. How can I prevent this? Thanks in advance. It follows some code:

$("#items").jqGrid({
                        height: 'auto',
                        url: "<%= Url.Content("~/EIDItems/getItems") %>",
                        datatype: 'json',
                        mtype: 'GET',
                        width: 500,
                        colNames: ['ItemId','ItemName'],
                        colModel: [
                                    { name: 'ItemId', index: 'ItemId', editable: false, resizable: true, sorttype: "int", width: 75, search: false },
                                    { name: 'ItemName', index: 'ItemName', editable: false, resizable: true, sorttype: "text", width: 75, search: true  }
                                  ],
                        pager: $('#item_pager'),
                        rowList: [10, 20, 30, 40, 50, 60, 70, 80, 90, 100],
                        rowNum: 10,
                        userdata: 'userdata',
                        sortname: 'ItemId',
                        sortorder: 'desc',
                        viewrecords: true,
                        imgpath: "<%= Url.Content("~/Content/jqGridthemes/steel/images") %>",
                        caption: 'Items',
                        multiselect: false,
                        toolbar: [true, "top"],
                        treeGridModel: 'adjacency',
                        ExpandColumn : 'ItemName',
                        treeGrid: true,
                        treeReader : { level_field: "level_field",parent_id_field: "parent_id_field", leaf_field: "leaf_field", expanded_field: "expanded_field" },
                        loadError:
                        function(xhr, st, err) {
                            showErrorMessage("Type: " + st + "; Response: " + xhr.status + " " + xhr.statusText);
                        },
                        loadComplete:
                        function() {
                            if($("#items").getUserData().TYPE == 'Error')
                            {
                                showErrorMessage($("#items").getUserData().MSG );
                            }
                        },
                     }).navGrid('#item_pager', { edit: false, add: false, del: false, search: true, refresh: true, refreshtext: "Refresh", searchtext: "Filter"}
                    )

The JSON of my test data looks like this:

{"total":7,"page":"1","records":"13 [13]","userdata":{"TYPE":"","MSG":""},"rows":[{"id":"5","cell":["5"
,"parent1",0,null,"false","false"]},{"id":"6","cell":["6","c2",1,5,"false","false"]},{"id":"7","cell"
:["7","c3",2,6,"true","false"]},{"id":"8","cell":["8","c1",1,5,"true","false"]},{"id":"9","cell":["9"
,"parent2",0,null,"false","false"]},{"id":"10","cell":["10","c5",1,9,"false","false"]},{"id":"11","cell"
:["11","c6",2,10,"true","false"]},{"id":"12","cell":["12","c4",1,9,"true","false"]},{"id":"13","cell"
:["13","p",0,null,"false","false"]},{"id":"14","cell":["14","b",1,13,"false","false"]},{"id":"15","cell"
:["15","c",2,14,"false","false"]},{"id":"16","cell":["16","d",3,15,"true","false"]},{"id":"17","cell"
:["17","a",1,13,"true","false"]}]}