I think the title says it all. When I try to use the <Separator /> tag to put a line in between elements in a stack panel in a UWP XAML app, I get this: 
When I hover over the separator elements it says that The type Separator cannot be found and gives the error code XLS0414.
Any ideas?
I've looked at many websites and they all say that I need to use the separator tag for what I'm trying to do, but I can't use it...