Selenium Silverlight:对象标识失败

我的selenium脚本返回一条错误消息，表示找不到对象。谁能确定我哪里出了问题

错误消息： com.thoughtworks.selenium.SeleniumException:错误：引发异常：document.slObject未定义

我测试的网页是：

页面的html代码是

<div id="silverlightControlHost" style="width: 720px; height: 520px;"><object id="slObject" data="data:application/x-silverlight-2," type="application/x-silverlight-2" width="100%" height="100%"><param name="source" value="/samplesbrowser/ClientBin/Infragistics.Web.SLDV.xap" /><param name="splashscreensource" value="splash.xaml" /><param name="onsourcedownloadprogresschanged" value="onSourceDownloadProgressChanged" /><param name="onsourcedownloadcomplete" value="onSourceDownloadComplete" /><param name="onError" value="onSilverlightError" /><param name="background" value="white" /><param name="minRuntimeVersion" value="4.0.50826.0" /><param name="windowless" value="false" /><param name="autoUpgrade" value="true" /><param name="culture" value="en-US" /><param name="uiculture" value="en-US" /><a href="http://go.microsoft.com/fwlink/?LinkID=149156&amp;v=4.0.50826.0" style="text-decoration: none"><img id="fallbackImage" src="http://go.microsoft.com/fwlink/?LinkId=161376" alt="Get Microsoft Silverlight"        style="border-style: none; width: 100%; height: 100%;" /></a></object><iframe id="_sl_historyFrame" style="visibility: hidden; height: 0px; width: 0px;border: 0px"></iframe></div>

---

我认为这应该在这里的问题清单上报告：

@Test
public void testPocAddCustomerHover() throws Exception {
    selenium.open(URL);
    //Thread.sleep(10000);
    silverLightApp = new Silvernium(selenium, "slObject");   
    selenium.windowMaximize();
      assertEquals(100, silverLightApp.actualWidth());

}