When you try to do step 4 from here:
http://docs.telerik.com/teststudio/features/testing-types/load-testing/add-custom-cookies

Test Studio crashes hard.

[08/19 14:20:16,Telerik.TestStudio.Desktop.exe(39728:1),Error] App.LogUnhandledException() : EXCEPTION! (see below)
     Situation: Unhandled exception!
     Outer Exception Type: System.Windows.Markup.XamlParseException
     Message: Provide value on 'System.Windows.StaticResourceExtension' threw an exception.
     HRESULT: 0x80131501 (Official ID (if app.) = COR_E_SYSTEM, Error Bit = FAILED, Facility = FACILITY_URT, Code = 5377)
     Call Stack:
          at System.Windows.Markup.WpfXamlLoader.Load(XamlReader xamlReader, IXamlObjectWriterFactory writerFactory, Boolean skipJournaledProperties, Object rootObject, XamlObjectWriterSettings settings, Uri baseUri)
          at System.Windows.Markup.WpfXamlLoader.LoadBaml(XamlReader xamlReader, Boolean skipJournaledProperties, Object rootObject, XamlAccessLevel accessLevel, Uri baseUri)
          at System.Windows.Markup.XamlReader.LoadBaml(Stream stream, ParserContext parserContext, Object parent, Boolean closeStream)
          at System.Windows.Application.LoadComponent(Object component, Uri resourceLocator)
          at Telerik.TestStudio.Load.Views.CookieScenarioStepEditorView.InitializeComponent()
          at Telerik.TestStudio.Load.Common.CookieScenarioStep.CreateStepEditorView(StepEditorContext editorContext)
          at Telerik.TestStudio.Load.Common.LoadDesignScenarioStepValueConverter.Convert(Object value)
          at Telerik.TestingFramework.Wpf.SimpleSingleValueConverterExtensionBase.Convert(Object value, Type targetType, Object parameter, CultureInfo culture)
          at System.Windows.Data.BindingExpression.TransferValue(Object newValue, Boolean isASubPropertyChange)
          at System.Windows.Data.BindingExpression.ScheduleTransfer(Boolean isASubPropertyChange)
          at MS.Internal.Data.ClrBindingWorker.NewValueAvailable(Boolean dependencySourcesChanged, Boolean initialValue, Boolean isASubPropertyChange)
          at MS.Internal.Data.PropertyPathWorker.UpdateSourceValueState(Int32 k, ICollectionView collectionView, Object newValue, Boolean isASubPropertyChange)
          at MS.Internal.Data.PropertyPathWorker.OnDependencyPropertyChanged(DependencyObject d, DependencyProperty dp, Boolean isASubPropertyChange)
          at MS.Internal.Data.ClrBindingWorker.OnSourceInvalidation(DependencyObject d, DependencyProperty dp, Boolean isASubPropertyChange)
          at System.Windows.Data.BindingExpression.HandlePropertyInvalidation(DependencyObject d, DependencyPropertyChangedEventArgs args)
          at System.Windows.Data.BindingExpressionBase.OnPropertyInvalidation(DependencyObject d, DependencyPropertyChangedEventArgs args)
          at System.Windows.Data.BindingExpression.OnPropertyInvalidation(DependencyObject d, DependencyPropertyChangedEventArgs args)
          at System.Windows.DependentList.InvalidateDependents(DependencyObject source, DependencyPropertyChangedEventArgs sourceArgs)
          at System.Windows.DependencyObject.NotifyPropertyChange(DependencyPropertyChangedEventArgs args)
          at System.Windows.DependencyObject.UpdateEffectiveValue(EntryIndex entryIndex, DependencyProperty dp, PropertyMetadata metadata, EffectiveValueEntry oldEntry, EffectiveValueEntry& newEntry, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType)
          at System.Windows.DependencyObject.SetValueCommon(DependencyProperty dp, Object value, PropertyMetadata metadata, Boolean coerceWithDeferredReference, Boolean coerceWithCurrentValue, OperationType operationType, Boolean isInternal)
          at System.Windows.DependencyObject.SetValue(DependencyProperty dp, Object value)
          at Telerik.Windows.Controls.Primitives.ItemsControlSelector.UpdatePublicSelectionProperties()
          at Telerik.Windows.Controls.Primitives.ItemsControlSelector.SelectionHelperSelectionChanged(Object sender, SelectionChangedEventArgs e)
          at Telerik.Windows.Controls.Primitives.SelectionHelper.<>c__DisplayClass2.<SelectionChangerSelectionChanged>b__0()
          at Telerik.Windows.Controls.Primitives.SelectionHelper.TryExecuteSelectionCallBack()
          at Telerik.Windows.Controls.Internal.ActiveSelectionScope.Dispose()
          at Telerik.Windows.Controls.Primitives.SelectionHelper.UpdateSelectionOnUserInteraction(Object item, SelectionMouseState mouseState)
          at Telerik.Windows.Controls.Primitives.ListItem.OnMouseLeftButtonDown()
          at Telerik.Windows.Controls.Primitives.ListItem.OnMouseLeftButtonDown(MouseButtonEventArgs e)
          at System.Windows.UIElement.OnMouseLeftButtonDownThunk(Object sender, MouseButtonEventArgs e)
          at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
          at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
          at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
          at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
          at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent)
          at System.Windows.UIElement.OnMouseDownThunk(Object sender, MouseButtonEventArgs e)
          at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
          at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
          at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
          at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
          at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args)
          at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args)
          at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
          at System.Windows.Input.InputManager.ProcessStagingArea()
          at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
          at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
          at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel)
          at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
          at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
          at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
          at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
          at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
          at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)

     Inner Exception Type: System.Exception
     Message: Cannot find resource named 'CheckBoxStyle'. Resource names are case sensitive.
     HRESULT: 0x80131500 (Official ID (if app.) = COR_E_EXCEPTION, Error Bit = FAILED, Facility = FACILITY_URT, Code = 5376)
     Call Stack:
          at System.Windows.StaticResourceExtension.ProvideValueInternal(IServiceProvider serviceProvider, Boolean allowDeferredReference)
          at System.Windows.StaticResourceExtension.ProvideValue(IServiceProvider serviceProvider)
          at MS.Internal.Xaml.Runtime.ClrObjectRuntime.CallProvideValue(MarkupExtension me, IServiceProvider serviceProvider)