Dim wb As New WeUI

With ExWeUI.WebUI.AddPullRefresh("pr01","pullcallback2",0,5) \'添加下拉刷新组件
    .scrollid= "in01"  \'指定嵌套的滚动组件的ID
    Dim html As String = "" \'用于记录滚动加载组件的html代码
    With ExWeUI.WebUI.AddExInfiniteScroll("in01","testcallback",0,8) \'添加滚动加载组件
        Dim wb2 As New weui \'用于生成默认列表
        With wb2.AddPanelGroup("","pg1","")
            Dim txt As String = "由各种物质组成的巨型球状天体,叫做星球.星球有一定的形状,有自己的运行轨道."
            For i As Integer = 1 To 8
                .Add("pn1" & i,"标题" & i,txt,"./images/button.png","http://www.foxtable.com")
            Next
        End With
        .Content = wb2.BuildHtml("pg1") \'设置默认显示的列表
        html = .BuildHtml
    End With
    .Content = html \'滚动加载组件html代码作为下拉刷新组件内部内容
    wb.InsertHTML(.BuildHtml)
End With
wb.AppendHTML("<script>initExWeUI();</script>")
output.show(wb.Build)

出现如图错误，这是怎么回事呢？