Code for counting visitors does not work

I have code for counting visitors but it does not work.

On Global.asax page:

Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)
Application("ClientsCount") = 0
End Sub

On starting page:

Dim count As Integer = 0

If Application("ClientsCount") IsNot Nothing Then
count = CInt(Application("ClientsCount"))
End If

count = count + 1
Application("ClientsCount") = count