DropShadowPanel and border corner radius

I want to make drop shadow effect with border control. I am using UWP toolkit.

<controls:DropShadowPanel x:Name="dspShadow"
                          BlurRadius="10"
                          ShadowOpacity="0.8"
                          OffsetX="0"
                          OffsetY="0"
                          Color="Black">
    <Border x:Name="borderMain" Background="Red" CornerRadius="10"/>
</controls:DropShadowPanel>

But it doesn't recognize corner radius, the result is like this:

And I need it to look like this:

Any ideas how to achieve this?