Can't see class defined in App_Code VS2010

I am using VS2010 and am creating an ASP.Net application.
I have declared a class called "Calculator" in a class file called "Calculator.cs" in the App_Code folder.
I have a form called "CalcDemo.aspx" with a code behind file. I try and use the "Calculator" class but intellisense can't see it. I thought App_Code is the common code repository for any classes I define and should be visible to all ASPX code behind files ..
The namespaces are the same like Webapp1.xxxx
Any advice on why the aspx file can't see this class ?


Giulio (aka "The Noob")


...