How can I make the Visual Studio 2008 to display Server Controls in the Toolbox

I'm developing an ASP.Net webapp, I've HTML controls and Server controls in my VS2008 Toolbox originally. However, the Server controls section was disappeared suddenly. How can I make them to be visible in the Toolbox?

Thank you开发者_Go百科!

BRs, William Choi

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Right click on the Toolbox and add references to the controls you need.