这段代码，为什么下载网页时不正常？

我用VBA写了一段代码，是用来下载单位内部网页的，我在工作薄的表6中A列加入了企业代码，然后用VBA依次读取企业代码填入查询框中，然后再网页框架中有企业信息，我找到了网页框架中的网址，直接登陆网址，下载企业信息，现在问题是我企业代码一个一个输入查询下载正常，但一旦把企业代码放入A列中读取自动填入框架中，自动查询网页也正常，但下载只能下载第一个循环，再次循环时就不能下载了。我写的的代码如下：

Sub 企业信息()
On Error Resume Next
    Dim mytrade As String, waitTime As String, ie As Object, y As Integer

Set ie = CreateObject("InternetExplorer.Application")

    intnum = Application.WorksheetFunction.CountA([A:A])
For y = 1 To intnum - 1
Application.ScreenUpdating = True

    mytrade = Sheet6.Cells(y + 1, 1).Value
   'mytrade = "4404110005"
     With CreateObject("InternetExplorer.Application")
        .Visible = True
        .Navigate "http://10.55.7.80/entmgr/App_Web/ent_base.aspx"
        Do Until .ReadyState = 4
            DoEvents
        Loop
        .Document.All("DropDownList1").Value = "trade_co"
        .Document.All("ZLTextBox7").Value = mytrade
       .Document.getElementById("Button2").Click
       waitTime = TimeSerial(Hour(Now()), Minute(Now()), Second(Now()) + 1)
Application.Wait waitTime

        .Document.getElementById("GridView1_ctl02_btnSelect").Click
         waitTime = TimeSerial(Hour(Now()), Minute(Now()), Second(Now()) + 1)
Application.Wait waitTime

      .Navigate "http://10.55.7.80/entmgr/App_Web/ent_baseinfo.aspx"
        waitTime = TimeSerial(Hour(Now()), Minute(Now()), Second(Now()) + 1)
Application.Wait waitTime
    n = Sheet1.Range("A65536").End(xlUp).Row + 1
        Set r = .Document.All.tags("table")(0).Rows
    For i = 0 To r.Length - 1
       For j = 1 To r(i).Cells.Length - 1 Step 2
            k = k + 1
            Sheet1.Cells(n, k) = r(i).Cells(j).innerText
        Next j
    Next i
Set r = Nothing
.Quit

End With
   Next y
End Sub
      --------------------编程问答-------------------- 用封包协议技术更好，速度能提高几百倍，一般情况下几百上千次也不大会出错 --------------------编程问答-------------------- 谢谢，能说详细点吗？

补充：VB ,  VBA