title: Problem with Visual Studio WPF Designer! :(
body: <p>Why i get this error:</p>
  
  <pre><code>'{DependencyProperty.UnsetValue}' is not a valid value for the 'System.Windows.Controls.Panel.Background' property on a Setter.
  </code></pre>
  
  <p>I'm sure that all controls styles, set well, But Visual Studio Designer display this error! :'( I'm sure that code is OK, and i don't want fill your browser screen with a lots of codes...</p>
  
  <p>I saw this error many times, and i don't know how debug it! Please help me, If u khow some debug tips!</p>
  
  <p>EDITED:</p>
  
  <p>in Player.xaml(UserControl):</p>
  
  <pre><code>&lt;Button Height="40" Name="btnNext"  Style="{StaticResource ResourceKey=NextButton}" Click="btnNext_Click" /&gt;
  </code></pre>
  
  <p>After i Rebuild the project, i saw error on the line above #:-s</p>
  
  <p>in Constants.xaml:</p>
  
  <pre><code>&lt;ImageBrush x:Key="nextImage" ImageSource="../Images/next.png" /&gt;
  </code></pre>
  
  <p>in Generic.xaml:</p>
  
  <pre><code> &lt;Style TargetType="{x:Type Button}" x:Key="NextButton"&gt;
          &lt;Setter Property="Background" Value="{StaticResource ResourceKey=nextImage}" /&gt;
          &lt;Setter Property="Template" Value="{StaticResource ResourceKey=PlayerButtonTemplate}" /&gt;
      &lt;/Style&gt;
  </code></pre>
  
  <p>Thanks in advance...:)</p>