Accessing User Control from Another Project

Hi all,

    First i created a Blank Solution say "MailApplication" under this i created two web Projects called "ProjectOne" and "ProjectTwo" - Framework 1.1 

    In ProjectOne i created a Folder as UserControls, in this i created a new User Control called "BottomBar.ascx".

    I tried to use this user control from ProjectTwo as per given below

    <%@ Register TagPrefix="BB" TagName="BottomBar" Src="../UserControls/BottomBar.ascx" %>

   <BB:BottomBar id="bottomBar" runat="server"></BB:BottomBar>

   but it throws following error as 

 The virtual path '/ProjectOne/UserControls/BottomBar.ascx' maps to another application, which is not allowed.

how to solve this problem, tha ...