Passing values between ASPX pages

Question

I currently have a webform with two different pages. The first page collects some preliminary information from the user and passes it using Server.Transfer to the second page which then echos the values the user entered. Everything works like a charm except that in the second page I already have already registered a TagPrefix and SourcePage to an ASCX page which a lot of error checking and logic that I wrote in JavaScript. When I click next on the first page and it executes the Server.Transfer to the second page, I get this error: Parser Error Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately. Parser Error Message: The virtual path '/userform/index.ascx' maps to another application, which is not allowed. Source Error: Line 1: <%@ Page Language="c#" ClassName="StepOne" Debug="true"%> Line 2: <%@ Register TagPrefix="IndexScript" TagName="ClientScript" Src="index.ascx" %> Line 3: