Error: AjaxControlToolkit requires ASP.NET Ajax 4.0 script

Hi,

I have Visual Studio 2012 Web Forms Application targeting 4.5 ,NET Framework. When using ajaxtoolkit 4.5 I got this error:

AjaxControlToolkit requires ASP.NET Ajax 4.0 scripts. Ensure the correct version of the scripts are referenced. If you are using an ASP.NET ScriptManager, switch to the ToolkitScriptManager in AjaxControlToolkit.dll

I already replaced Script Manager by ToolKitScriptManager, but it's not resolved yet. Also I tried other solutions after long research in the internet but no luck.

Any Help!...