silverlight page switch

Well I am getting an error on the bold liine in main.xaml. I have added page1.xaml and page2.xaml. I want to click a button in main and switch to a page1 or page2.

.Error    1    The tag 'Frame' does not exist in XML namespace 'http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk'.    D:\silverlight\nav1\nav1\MainPage.xaml    13    10    nav1
Error    2    The type 'ResourceDictionary' is inside a ResourceDictionary and does not have a key.    D:\silverlight\nav1\nav1\App.xaml    nav1


main.xaml

<UserControl
    x:Class="nav1.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
    xmlns:uriMapper="clr-namespace:System.Windows.Navigation;assembly=System.Windows.Controls.Navigation"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
     xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk"
    mc:Ignorable="d" d:DesignWidth="640" d:DesignHeight="480">

    <Grid x:Name="LayoutRoot" Margin="0">

        <sdk:Frame x:Name="Page1" UriMapper="{StaticResource GameUriMapper}"/>

    </Grid>

</UserControl>

app.xaml


<Application  
  x:Class="nav1.App"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:navigation="clr-namespace:System.Windows.Navigation;assembly=System.Windows.Controls.Navigation"
    
    >
    <Application.Resources>
        <navigation:UriMapper x:Key="GameUriMapper">

            <navigation:UriMapping Uri="{}{page}" MappedUri="/{page}.xaml"/>

        </navigation:UriMapper>



        <ResourceDictionary>
      <ResourceDictionary.MergedDictionaries>
        <ResourceDictionary Source="Assets/Styles.xaml"/>
      </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
  </Application.Resources>

</Application>


main.xaml.vb

   Private Sub MainPage_Loaded(ByVal sender As Object, ByVal e As System.Windows.RoutedEventArgs) Handles Me.Loaded
        bt.Width = 200
        bt.Height = 100
        AddHandler bt.Click, AddressOf bt_click

    End Sub

    Public Sub bt_click(ByVal sender As Object, ByVal e As RoutedEventArgs)
        PageFrame.Navigate(New Uri("Level1", UriKind.Relative))
    End Sub

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<UserControl x:Class="SilverlightApplication34.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation"
    xmlns:local="clr-namespace:SilverlightApplication34">
    <Grid x:Name="LayoutRoot" Background="{StaticResource ApplicationBackgroundColorBrush}">
        <Grid.Resources>
            <local:VisibilityBooleanConverter x:Key="VisBool" />
        </Grid.Resources>

            <Grid Style="{StaticResource NavigationContainerStyle}">

            <Border Style="{StaticResource NavigationBorderStyle}">
            
                <StackPanel Style="{StaticResource NavigationPanelStyle}">

                    <Button Click="NavButton_Click" Tag="/Views/HomePage.xaml" Content="home" 
                            Style="{StaticResource PageLinkStyle}"/>
                    <Button Click="NavButton_Click" Tag="/Views/AboutPage.xaml" Content="about" 
                            Style="{StaticResource PageLinkStyle}"/>
                            
                            <Button Click="NavButton_Click" Tag="/Views/SubNavigation.xaml" Content="sub navigation" 
                            Style="{StaticResource PageLinkStyle}"/>
                
                </StackPanel>
            
            </Border>
            
            <Border Style="{StaticResource BrandingBorderStyle}">
            
                <StackPanel Style="{StaticResource BrandingPanelStyle}" x:Name="JournalNav">
                
                    <Button Content="back" Style="{StaticResource PageLinkStyle}" x:Name="NavBack" Click="NavBack_Click" />
                    <Button Content="forward" Style="{StaticResource PageLinkStyle}" x:Name="NavFwd" Click="NavFwd_Click" />

                </StackPanel>
                
            </Border>
            
        </Grid>

        <Border Style="{StaticResource FrameContainerStyle}">

            <Border Style="{StaticResource FrameInnerBorderStyle}">

                <navigation:Frame Navigated="Frame_Navigated" x:Name="Frame" Source="/Views/HomePage.xaml"
                                  HorizontalContentAlignment="Stretch"
                                  VerticalContentAlignment="Stretch"
                                  Padding="15,10,15,10"
                                  Background="White"/>

            </Border>

        </Border>

    </Grid>
</UserControl>

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<Application   
  x:Class="nav1.App"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:navigation="clr-namespace:System.Windows.Navigation;assembly=System.Windows.Controls.Navigation"
  
    >
    <Application.Resources>
        <navigation:UriMapper x:Key="GameUriMapper">

            <navigation:UriMapping Uri="{}{page}" MappedUri="/{page}.xaml"/>

        </navigation:UriMapper>



        <ResourceDictionary>
      <ResourceDictionary.MergedDictionaries>
        <ResourceDictionary Source="Assets/Styles.xaml"/>
      </ResourceDictionary.MergedDictionaries>
    </ResourceDictionary>
  </Application.Resources>

</Application>

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