Can't get Theme Variations working

[Bart]

I've just started working with Telerik UI for WPF and have been working with implicit styles. I got the implicit styles working but haven't been able to access the theme variations as detailed in the documentation. I inserted the variation code into my code-behind file as shown below:

 public partial class MainWindow : Window
    {
        public MainWindow()
        {
            //dark color variation
            VisualStudio2013Palette.LoadPreset(VisualStudio2013Palette.ColorVariation.Dark);
            InitializeComponent();
        }
    }

But get the following error message:

Error 1 The name 'VisualStudio2013Palette' does not exist in the current context 

Any ideas?

[Bart]

D'oh! Forgot to add 'using Telerik.Windows.Controls;'

fixed.