CenterButtonBorderThickness Throws conversion Error

[PL76]

Following error is thrown when compiling which is causing most other property settings to not take place:
Converter failed to convert value of type 'Windows.Foundation.Double' to type 'Thickness'; BindingExpression: Path='CenterButtonBorderThickness' DataItem='RadialMenuControl.UserControl.RadialMenu'; target element is 'RadialMenuControl.Components.CenterButton' (Name='CenterButton'); target property is 'BorderThickness' (type 'Thickness').

I tried setting a value for CenterButtonBorderThickness but then the error just appears twice in the Output window.