Silverlight AG_E_UNKOWN_ERROR UserControl Apps.xml Template - xaml

Question

Ive created a simple usercontrol and even though the app runs ok applying the template to
I am defining the Control Template here
App.xaml
<Application xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Class="ResourcesCountDown.App"
>
<Application.Resources>
<ControlTemplate x:Key="myWindowTemplate">
<Grid x:Name="myGrid" Background="Black" Width="50" Height="50">
<ContentPresenter Name="Content"></ContentPresenter>
</Grid>
</ControlTemplate>
</Application.Resources>
</Application>
My UserControl Test.xaml
<UserControl x:Class="ResourcesCountDown.Test"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Width="100" Height="100" >
<Grid x:Name="LayoutRoot">
<Button Name="myButton" Template="{StaticResource myWindowTemplate}" Foreground="White" Content="CLICK" ></Button>
</Grid>
</UserControl>
My page where the user control is being used and the page where the AG E UNKOWN_ERROR occurs.
If I remove applying the template from test.xaml and remove the Template="{StaticResource myWindowTemplate}" the error goes away, so I know its something BAD in my template definition?
Mainpage.xaml
<UserControl x:Class="ResourcesCountDown.Mainpage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:ResourcesCountDown="clr-namespace:ResourcesCountDown"
xmlns:sliverlightControls="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Toolkit"
Width="Auto" Height="Auto" Name="mainPage"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d">
<Grid x:Name="LayoutRoot" Background="White" ShowGridLines="False" >
<Grid.ColumnDefinitions>
<ColumnDefinition Width="10"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="10"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="10"/>
<RowDefinition Height="80"/>
<RowDefinition Height="10"/>
<RowDefinition Height="*"/>
<RowDefinition Height="10"/>
</Grid.RowDefinitions>
<Border Grid.Column="1" Grid.Row="1" Height="Auto" VerticalAlignment="Top" CornerRadius="5">
<Border.Background>
<LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
<GradientStop Color="#FFFFAA01"/>
<GradientStop Color="#FFFD6900" Offset="1"/>
</LinearGradientBrush>
</Border.Background>
<Grid x:Name="TopBannerGrid">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="300"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="500"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<ResourcesCountDown:LogoControl Width="Auto" Height="Auto" Grid.ColumnSpan="2" Margin="5,0,0,0"/>
<ResourcesCountDown:MenuControl Grid.Column="2" HorizontalAlignment="Right" x:Name="menu" Margin="0,-30,0,0"/>
</Grid>
</Border>
<sliverlightControls:WrapPanel Width="900" Height="600" Grid.Column="1" Grid.Row="3" Orientation="Vertical" HorizontalAlignment="Left" VerticalAlignment="Top" >
<ResourcesCountDown:noteControl Width="200" Height="200" headingText="Whats it about?" Margin="10"
noteText="We have one planet with finite resources. This web site was created to try and express the resource consumption.">
</ResourcesCountDown:noteControl>
<ResourcesCountDown:noteControl Width="200" Height="200" headingText="Latest News" Margin="10"
noteText="This week we have see some many new news in just a short time">
</ResourcesCountDown:noteControl>
<ResourcesCountDown:RSSFeed Width="600" Height="200" Margin="10" headingText="Hot News"/>
<ResourcesCountDown:datagridControl Width="600" Height="100" x:Name="theDataGrid" Margin="10" headingText="Stats" > </ResourcesCountDown:datagridControl>
<ResourcesCountDown:Test></ResourcesCountDown:Test>
</sliverlightControls:WrapPanel>
</Grid>
</UserControl>

Answer 1

I think you need a TargetType="Grid" on your <ControlTemplate>:
<ControlTemplate x:Key="myWindowTemplate TargetType="Grid">
....
Also, Grid isn't a ContentControl so I don't think the ContentPresenter you put in the template will behave the way you expect - it could even be causing the error.

Answer 2

Actually, from the code you've posted, your TargetType should be Button because you're applying the template to button.