主题：这个错误怎么解决

Dim web As New System.Windows.Forms.WebBrowser()
web.Navigate("http://vip.stock.finance.sina.com.cn/mkt/#all_forex")
Do Until web.ReadyState = 4
    Application.DoEvents
Loop
MessageBox.Show("等待数据加载完成")

Dim elems As object = web.Document.GetElementById("list_amount_ctrl").GetElementsByTagName("a")
For Each elem As object In elems
    If elem.InnerText = "80" Then
        elem.InvokeMember("click")
    End If
Next

elems = web.Document.GetElementById("tbl_wrap").GetElementsByTagName("tr")
MessageBox.Show("共获取 " & elems.count-1 & " 条数据")