Visual Studio 2010中的Ajax 3.5

I had convert my web application from visual studio 2003(framework 1.1) to visual studio 2010(framework 4.0). After converted, I have pug-in Ajax 3.5 and test my web application. The web application run well but the Ajax doesn't work. There are not error appear in the application also.

What can I do in other to make the Ajax work???

Please advice...Thanks in advance.

Here is the solution:

1. just remove the script managers from the pages and add it again how it was, from the Visual Studio tool box.
2. close the browser and run it.

It should work fine.