dynamically binding styles to grid

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XAML

Silverlight

style

hello
iam practice the silverlight examples

so in my application have a grid having stles so this styles is (Assets/Styles.xaml)
there

in codebehind iam wrote like this

ResourceDictionary r = new ResourceDictionary();
r.Source = new Uri("/Assets/Styles.xaml", UriKind.Relative);
Style s = (Style)r["BigGridStyle"];
PageContainer.Style = s;

in styles.xaml page wrote like this

<Style x:Key="BigGridStyle" TargetType="Grid">
           <Setter Property="Background">
               <Setter.Value>
                   <LinearGradientBrush StartPoint="0,0" EndPoint="1,0">
                       <GradientStop Color="Blue"></GradientStop>
                       <GradientStop Color="Yellow" Offset="1"></GradientStop>
                   </LinearGradientBrush>
               </Setter.Value>
           </Setter>
       </Style>

in xaml page binding staticresource like this

<Grid x:Name="PageContainer" Margin="47,224,49,207" Style="{StaticResource BigGridStyle}"   />

but it's not working for me it's giving error
like this
Error:

[Arg_COMException]
Arguments:
Debugging resource strings are unavailable. Often the key and arguments provide sufficient information to diagnose the problem. See http://go.microsoft.com/fwlink/?linkid=106663&Version=5.0.60401.00&File=mscorlib.dll&Key=Arg_COMException

So can you any one tell me where i wrong?

Thanks & Advance