COOKIE为什么取值问题

Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
'If Not Page.IsPostBack Then
Dim vote_name
Dim vote_item

vote_item = Request("vote_item")
vote_name = Request("vote_name")
DataGrid1.Caption = vote_name

'==================================================================test
'Label4.Text = Response.Cookies.Item("mysite_cookie").Value

'Dim i As Integer
'For i = 0 To Request.Cookies.Count - 1
' Response.Write("name:" & Request.Cookies.Item(i).Name & "<br>")
' Response.Write("value:" & Request.Cookies.Item(i).Value & "<br>")

'Next
'If Response.Cookies.Item("mysite_cookie").Value <> "vote_ok" Then
' Response.Write("vote_ok is <>")
'End If
'==============================================================



'设置投票数据更新
If Response.Cookies.Item("mysite_cookie").Value <> "vote_ok" Then
Response.Cookies.Item("mysite_cookie").Expires = Now.AddDays(3)
Response.Cookies.Item("mysite_cookie").Value = "vote_ok"

Dim updatesqlstring As String
updatesqlstring = "update voteitem set item_count = item_count + 1 where item_id = " & vote_item
Dim updatecommand As OleDbCommand = New OleDbCommand(updatesqlstring, OleDbConnection1)
OleDbConnection1.Open()
updatecommand.ExecuteNonQuery()
OleDbConnection1.Close()
Label3.Text = "投票成功！"
Else
Label3.Text = "您已经投过票了！请查看投票结果。"
End If

'取得投票列表
Dim sqlstring As String
Dim mycommand As OleDbCommand
sqlstring = "select item_name,item_count,vt_id from voteitem where "
sqlstring += "vt_id = (select vt_id from voteitem where item_id = " & vote_item & ")"
mycommand = New OleDbCommand(sqlstring, OleDbConnection1)
Dim mydataadapter As New OleDbDataAdapter(mycommand)
mydataadapter.Fill(DataSet11, "voteitem")

Page.DataBind()
'End If

End Sub
问题：If Response.Cookies.Item("mysite_cookie").Value <> "vote_ok" Then 为什么取值总是不等于"vote_ok",另外，还请教能不能动态的设定COOKIE 的NAME值，防止重复投票上是怎么处理的？