Why is 'BusyIndicator' not found?

I am using Silverlight 5 toolkit and I am references that version of Silverlight.Windows.Controls.Toolkit in my silverlight demo.

But I get this error and I do not know what to do

Error 16 The tag 'BusyIndicator' does not exist in XML namespace 'clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Toolkit'. C:\Users\Bobbi\Documents\Visual Studio 2012\Projects...

How do I get the code to compile?

You'll need to add an explicit refrence to it in the XAML, kind of like using namespace ... ;. The MSDN has some documentation on this here. Basically, you add it to the root element it like so:


Where you'd replace <assembly_name> with the actual name of the assembly (without the .dll). You then reference it using the namespace you defined (in this case I used tk):