jqgrid treegrid树形表格

一下代码是加载树形的结构的部分代码，，树形表折叠功能不好用
_grid.jqGrid({
           //caption: "<b>"+scope.$menu.text+"</b>",
           width:scope.centerWidth - 2 - 10,
           height:scope.centerHeight - 70 - 10,
           colModel:scope.columns,
           shrinkToFit:false,
           //
           ExpandColumn:"code_tree",
        treeGrid: true,
        treeGridModel:"adjacency",
        datastr:[],
        "datatype":"jsonstring",
        treeIcons: {leaf:'ui-icon-document-b'},
        treeReader:{
            parent_id_field: "parent",   
"level_field":"level",
"leaf_field":"isLeaf",
"expanded_field":"expanded",
"loaded":"loaded",
"icon_field":"icon"
        },
图片中圈出的箭头点击没有效果，自己认为应该是哪个treegrid属性冲突，自己找了很长时间了，没找到，求大神解答