sharing web user control between projects

I have 2 different projects, one that has **just** a web user control ("UC"), and another one that wants to reference and use that project ("PARENT").

I've referenced the "UC" project in the "PARENT" but when I try to add a reference to the .ascx that resides inside of "UC", I get an error at runtime:

http:/localhost/DealerSocket.Web.Common.UserControls/uc_DatePicker.ascx' is not a valid virtual path.

I've added the "UC" project as a virtual path, so I am not sure what more I can do.

web page (.aspx) markup:

<%@ Register src="http://localhost/DealerSocket.Web.Common.UserControls/uc_DatePicker.ascx" tagname="uc_DatePicker" tagprefix="uc2" %>

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then futher down:

<uc2:uc_DatePicker ID="uc_DatePicker1" runat="server" />

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How do I correct this problem?

Also I've removed the block for .ascx file types in IIS so it's not that.