Local xaml namespace works for compiling dll, but breaks when using the dll

Question

I have a dll that includes a wpf window that references a local namespace in xaml. That local namespace is used to reference a class in the same project with the same namespace.

    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:selectedOption="clr-namespace:COD.GISTools.DallasExport"
    Title="Pick an Export option:" Height="200" Width="300">
    <Window.Resources>
        <selectedOption:EnumBooleanConverter x:Key="enumConverter" />

It works fine when compiling the dll. When I reference the compiled dll in my application and try to debug it, though, I get a "Assembly must be specified for XAML files that are not part of a project" error, and my application won't run. I don't understand where I'm going wrong?