How to show sub-menus in Menu control in ASP NET?

I am learning and using VS 2005 to design a website. I used the Menu control to create a menu with some items and some sub-items开发者_JS百科, for instance: Home Product Phone Cars News

However, when I run the web page and hover the mouse over the Product menu, its sub-menus did not show up.

Did I miss something? Do I have to do anything else?

Thanks a lot?

Here is a good tutorial / overview for the menu control. The section that covers Static / Dynamic Display may be pertinent to your question.