Enter value in DateEdit

Question

<dxl:LayoutItem Label="Startdate:">
      <dxe:DateEdit Name="StartDateEdit" 
                    Text="{Binding StartDate, TargetNullValue=''}" 
                    MaskUseAsDisplayFormat="True"
                    MinValue="{Binding MinStartDate}" 
                    MaxValue="{Binding MaxStartDate}"/>
</dxl:LayoutItem>

The dates are displayed 2017-12-13 and when I highlight 2017 to change it, I can only changes it with the arrows keys.

But I want to press the number keys 2018 but it only changes the the last digit, so when I have written 2018 it says 2008.