UserControl in the same Project

Hello everyone:

I have a Project where there is a Folder with UserControls. The idea is call each UserControl in a Main Panel. By the way, i have a WPF Browser Application.

This is the Page1.xaml code. Please, note this:

<Page
x:Class="WpfBrowserApplication1.Page1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:MiControl="clr-namespace:WpfBrowserApplication1.ControlesDeUsuario"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
Title="SysGestión - Módulo de Contabilidad">

The name folder is "ControlesDeUsuario". When i start up the Project, the Visual Studio give me this message: "There is no source code available".

The code to call the UserControl is:

<MiControl:CU_Mantencion_Profesionales x:Name="CU_MP"/>

And, finally, the UserControl name is "CU_Mantencion_Profesionales".

Thank you guys!