Microsoft.Phone.Controls.Toolkit unable to import using directive

I have downloaded and installed Microsoft.Phone.Controls.Toolkit and I am able to include it in the xaml page, but I am unable to include it in the C# file(lik开发者_如何学Ce "using Microsoft.Phone.Controls.Toolkit" ). any idea why this happens?

For the xaml:

xmlns:toolkit="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone.Controls.Toolkit"

You can use the controls in the C# file after you add the code post above.

...try to build and after add

using Microsoft.Phone.Controls.Toolkit;

Did you add the DLL as a reference to the project?