DOJO 工具提示给出“未捕获的类型错误:对象不是函数”

我有以下代码尝试使用dojox/charting/action2d/Tooltip：

require([
    "dojox/charting/Chart",
    "dojox/charting/themes/Claro",
    "dojox/charting/plot2d/MarkersOnly",
    "dojox/charting/plot2d/Columns",
    "dojox/fx/easing",
    "dojox/charting/action2d/Tooltip",
    "dojox/charting/axis2d/Default",
    "dojo/ready"
], function(Chart, Theme, MarkersOnly, easing, Tooltip, Columns, Default, ready) {
        ready(function(){
                var chart1 = new Chart("chartArea");
                chart1.setTheme(Theme);
                chart1.addPlot("budget", {type: "MarkersOnly"});
                chart1.addPlot("actual", {type: "Columns", gap: 3, animate: { duration: 300, easing: dojox.fx.easing.linear}});
                //add the axis (both x and y) below
                chart1.addAxis("x",{labels: [
                    {value:1, text: "01 - AXA"},{value:2, text: "02 - MR"},{value:3, text: "03 - CT"},{value:4, text: "04 - XP WH"},                                              
                    {value:5, text: "06 - XP RF"},{value:6, text: "07 - XPC"},{value:7, text: "09 - ECS"},{value:8, text: "10 - XPU"}], 
                     rotation:-90, 
                     font: "normal normal bold 12pt Arial"
                });//end adding axis to the chart
                chart1.addAxis("y", {vertical: true, font: "normal normal bold 12pt Arial"});
                chart1.addSeries("Series 2", [80,80,80,80,80,80,80,80,80,80,80,80,80], {plot:"budget"});
                //chart1.addSeries("Series 1", [73,71,78,93,70,,,83,100,,,], {plot:"actual"});
                chart1.addSeries("Series 1", [{y:75, tooltip:"custom"},{y:71},{y:78},{y:93},{y:70},{y:83},{y:100}], {plot:"actual"});

                var tip = new Tooltip(chart1, "default");  
                chart1.render();
        });//end of DOJO ready
    });//end function chart stuff

DOJO给了我以下错误：

Uncaught TypeError: object is not a function

我可以弄清楚为什么会出现这个问题，特别是因为我发现多个示例以这种方式处理它。 有人知道吗？