root element is not valid for navigation

Good Day i have a Window in WPF defined like this 

 

<Window x:Class="RVI_Education.Gavigator"        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"        Title="Gavigator" Height="673.2" Width="1304.4">    <Frame Name="FrameWithinGrid" >    </Frame></Window> 

and im using it as a start up in my app.xaml

 <Application x:Class="RVI_Education.App"             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"             StartupUri="Gavigator.xaml">    <Application.Resources>             </Application.Resources></Application>  

and on Window loaded event i navigate to another Window 

like this 

 
 

  public Gavigator()        {            InitializeComponent();            Loaded += Gavigator_Loaded;                   }        void Gavigator_Loaded(object sender, RoutedEventArgs e)        {           FrameWithinGrid.Navigate(new System.Uri("Splash.xaml",UriKind.RelativeOrAbsolute));        } 

 
when i load the Project i get an Error 
 
 
 RVI_Education.Splash' root element is not valid for navigation. 

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Vuyiswa Maseko