Commented Unassigned: 'Initialization of 'Xceed.Wpf.Toolkit.RangeSlider' threw an exception in VS2015 CTP6 [21739]

Since installation of Visual Studion 2015 CTP6 RangeSlider gives as runtime error:

{"'Initialization of 'Xceed.Wpf.Toolkit.RangeSlider' threw an exception.' Line number '87' and line position '189'."}

{pack://application:,,,/Coolblue.Purchasing.CompetitorPricing;component/views/elasticitysettingsview.xaml}

{"Initialization of 'Xceed.Wpf.Toolkit.Core.VersionResourceDictionary' threw an exception."}

{"Cannot locate resource 'xceed.wpf.toolkit;v2.3.0.0;themes/xceed.wpf.toolkit;v2.3.0.0;component/themes/aero/brushes_normalcolor.xaml'."}

This did not happen before in Visual Studio 2015 Preview.

Dit something change in VS2015 CTP6 that broke this?

Thanks in Advance for any answers,
Antoni Dol
Comments: ** Comment from web user: killnine **

Same thing happening for me, except with WatermarkTexBox.

Not sure what else to do, as this works fine on VS2013 SP4.