I'm using ajax control toolkit in the default asp.net forms project created in VS2012. Basically I add the ToolkitScriptManager and TextBoxWatermarkExtender to test if the toolkit works well. I get the following error when running the application. It seems to remind me to use ToolkitScriptManager instead of asp.net script manager, but I have replace the normal asp.net script manager with ToolkitScriptManager. Does anyone know what causes this issue?
__Unhandled exception at line 3, column 412 in http://localhost:36907/default.aspx?_TSM_HiddenField_=MainContent_tkScriptManager1_HiddenField&_TSM_CombinedScripts_=;;AjaxControlToolkit,+Version=4.5.7.123,+Culture=neutral,+PublicKeyToken=28f01b0e84b6d53e:en-US:e669ce41-1aa1-4541-aae9-fa5dc37e70db:de1feab2:f9cec9bc:35576c48
0x800a139e - JavaScript runtime 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.__
__Unhandled exception at line 3, column 412 in http://localhost:36907/default.aspx?_TSM_HiddenField_=MainContent_tkScriptManager1_HiddenField&_TSM_CombinedScripts_=;;AjaxControlToolkit,+Version=4.5.7.123,+Culture=neutral,+PublicKeyToken=28f01b0e84b6d53e:en-US:e669ce41-1aa1-4541-aae9-fa5dc37e70db:de1feab2:f9cec9bc:35576c48
0x800a139e - JavaScript runtime 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.__