TypeError：$（...）。jqxTree不是函数

Question

我正在尝试绑定树但是获取TypeError。 json值在jqwidgets树中没有绑定。我只是在Head Tag中添加插件并声明它。

myCode：

<script type="text/javascript" src="assets/jtree/jquery-1.10.2.min.js"></script>    
<script type="text/javascript" src="assets/jtree/jqxcore.js"></script>    
<script type="text/javascript" src="assets/jtree/jqxbuttons.js"></script>
<script type="text/javascript" src="assets/jtree/jqxscrollbar.js"></script>
<script type="text/javascript" src="assets/jtree/jqxpanel.js"></script>
<script type="text/javascript" src="assets/jtree/jqxtree.js"></script>

jQuery(document).ready(function () {
     LoadOrgUnitData();
});

function LoadOrgUnitData() {                        
                var source = [
            { label: "Item 1", expanded: true, items: [
                { label: "Item 1.1" },
                { label: "Item 1.2", selected: true }
            ]
            },
            { label: "Item 2" },
            { label: "Item 3" },
            { label: "Item 4", items: [
                { label: "Item 4.1" },
                { label: "Item 4.2" }
            ]
            },
            { label: "Item 5" },
            { label: "Item 6" },
            { label: "Item 7" }
        ];
    // Create jqxTree.
                alert(source);

                $('#jqxTree').jqxTree({ source: source, height: '300px', width: '300px' });             
}