I'm trying to use AjaxControlToolkit controls (specifically CalendarExtender and ComboBox), but am having problems with the ScriptManager control. I've got the ToolkitScriptManager at the top of the form, but when I load the page, I get this error:
Only one instance of a ScriptManager can be added to the page.
As soon as I removed the ScriptManager, I get this error:
Microsoft JScript 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.
I haven't added any other script managers anywhere else, and I've got the (.NET 3.5) DLL registered in GAC, and copies in the application's bin and _app_bin folders.
What's going on?