With the RadMaskedEditBox and MaskType set to Numeric and using simple data binding the mask is not being displayed properly

As a workaround handle ValueChanged event and apply the formatting in this event:
       dim alreadyExecuted as Boolean
       Sub ValueChange(sender As Object, e As EventArgs) Handles EditBoxWithBinding.ValueChanged 
	If Not alreadyExecuted Then 
		alreadyExecuted = True EditBoxWithBinding.MaskedEditBoxElement.Provider.Validate(EditBoxWithBinding.Value.ToString()) 
		alreadyExecuted = False 
	End If 
End Sub