换了个页面就获取不了SESSION的值解决思路

<%
sub addtocart() 


ProductList = Session("ProductList")
Products = Split(Request("Prodid"), ",")
For I=0 To UBound(Products)
   PutToShopBag Products(I), ProductList
Next
Session("ProductList") = ProductList

if request("payment")="去收银台" then
response.redirect "b2b_ddlcsys.asp?action=1"
end if

If Request("cmdShow") = "Yes" Then
   ProductList = ""
   Products = Split(Request("ProdId"), ", ")
   For I=0 To UBound(Products)
      PutToShopBag Products(I), ProductList
   Next
   Session("ProductList") = ProductList
End If
If Len(Session("ProductList")) = 0 Then
end if
%>
<%
Set rsCheck=Server.CreateObject("ADODB.RecordSet") 
strsql="select id,name,price,amount,stock from Product where ID in ("&Session("ProductList")&") order by ID"
rsCheck.open strsql,conn,1,1
%>
<link href="b2b_includefile/css.css" rel="stylesheet" type="text/css">

<table width="96%" border="0" cellspacing="0" cellpadding="0" align="center">
<tr> <form action="check.asp" method="POST" name="check"><td>

      <table border="0" cellspacing="1" cellpadding="4" align="center" width="100%" bgcolor="#f2f2f2">
            <tr bgcolor="#f7f7f7" height="25" align="center"> 
            <td width="40"><strong>编 号</strong></td>
            <td width="300"><strong>商 品 名 称</strong></td>
            <td width="40"><strong>数量</strong></td>
            <td width="60"><strong>成交价</strong></td>
            <td width="70"><strong>总 计</strong></td>
          </tr>
<%
Sum = 0
Quatity = 1
Do While Not rsCheck.EOF
     Quatity = CInt( Request.Form( "Q_" & rsCheck("ID")) )
     If Quatity <= 0 Then 
        Quatity = CInt( Session(rsCheck("ID")) )
        If Quatity <= 0 Then Quatity = 1
     End If
Session(rsCheck("ID")) = Quatity

IF rsCheck("Stock") < Quatity Then
Quatity = 1
Session(rsCheck("ID")) = 1
response.write "<script language=javascript>alert('对不起，"&rsCheck("Name")&"暂时库存不足！');window.close();</script>" 
Response.End()
Conn.Close
Set Conn = Nothing
End IF

Dim Price

Price =  Round(rsCheck("Price"),2)
Sum = Sum + price*Quatity
Sum=Round(Sum,2) 
%>