Page_Unload event in a ASP.net project

I am creating a web site in VB.net and I found the need to save information into a session variable for the next page to consume when it loads so I placed the code to save the value into the Page_Unoad event of all my pages. When I tested it the value was not saved so I set break points only to find that the Page_Unload event never fires at all??????

If this never fires why have it?

I am using a Master page senerio if that makes a diffrence.

Thanks,

Ty
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