I am having some basic compile issues defining a BorderBrush in my Silverlight C# file.

states that you define a borderbrush like this:

myBorder1 = new Border();
myBorder1.BorderBrush = Brushes.SlateBlue;
but in my code, when I try
border1.BorderBrush = Brushes.SlateBlue;
I get
Error 1 The name 'Brushes' does not exist in the current context
and I have included the namespace
as a "using" statement at the top of the file
as well as a Reference to the project.
What am I missing?