member level variable scope

 
I have a member (class level) C# variable in my .aspx page.  I have it declared as a programmer defined class ( selectedProduct) of type product.  After initially instantiating the variable and populating its fields, it becomes null again when trying to access it from a different method.  Shouldn't a member level variable still be instantiated when accessing it from a different method?  Or will I need to store the instantiated and populated class in a session variable for later use?
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