Hello Priya Ramesh,
1. Try using ToolkitScriptManager. The 4.0 Control Toolkit uses their own version of "MicrosoftAjax.js" and "MicrosoftAjaxWebForms.js" registered by the ToolkitScriptManager.
2. You can take a look at this public forum thread
which elaborates on the same subject. Check whether youare using the .NET 4 assemblies
of RadControls for ASP.NET AJAX in your project.
3. If you are using ASP.NET ScriptManager or RadScriptManager you should register the scripts manually by specifying the path the the Microsoft Ajax js library.
4. There is a known issue about RadAjaxManager and AjaxControlToolkit which should be fixed int the latest internal build of the RadControls for ASP.NET AJAX. There are some known issues that still appear when you have enabled Telerik CDN.
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