How to Toggle a Session Variable between two values?

I've got a button I'm trying to use to toggle a Session Variable between two values.

In Page_Load I set:
Session("Filter") = 1

Then in the button:
If  Session("Filter") = 1 Then
Session("Filter") = 2
Else
Session("Filter") = 1
End If

But it stays "1".  I know it's the Page_Load setting it back to 1, but how do I make it work correctly?

Oh, if I refresh the page (completely) then it reverts to the original value, which is good.  I tried this:

Response.Redirect("http://www.mypage.aspx")

but it didn't refresh completely.
LVL 1
megninAsked:
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CodeCruiserCommented:
Change this

In Page_Load I set:
Session("Filter") = 1

to

In Page_Load I set:
If Page.IsPostBack = False Then
   Session("Filter") = 1
End If

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megninAuthor Commented:
Ahh, yes.  I think that should do it.
megninAuthor Commented:
That, it did.  Thank you!!
CodeCruiserCommented:
Glad to help :-)
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