visual studio Microsoft JScript runtime error: 'Sys' is undefined error

my visual studio automatically inserts this

<script type='text/javascript'>new Sys.WebForms.Menu({ element: 'NavigationMenu', disappearAfter: 500, orientation: 'horizontal', tabIndex: 0, disabled: false });</script></form>

code on debugging (it is a default.aspx with default masterpage), which seems to cause the error message with the content

Microsoft JScript runtime error: 'Sys' is undefined

to appear any time I debug a project.

Does anyone know how to solve this visual studio problem? I am not using ajax. It is开发者_Go百科 just default.

Also breakpoints are not hit!!!

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Add a script manager to the master page.

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If you already have a scriptmanager on the page and it still doesnt work, then place the <script> tag some place after where you put your scriptmanager.