Could not find any resources appropriate for the specified culture or the neutral culture. Make sure "AjaxControlToolkit.Properties.Resources.NET4.resources" was correctly embedded or linked into assembly "AjaxControlToolkit" at compile time, or that all the satellite assemblies required are loadable and fully signed.
The working environment is the same as in http://hilaltarakci.blogspot.com/2012/09/using-calendarextender.html.
I have a user control using ajax control toolkit components and i am pretty sure this control works properly on its own. However, when i tried to use the control in another control, i got the above error.
In my case, adding the following lines to the caller user control fixed my problem:
<asp:ScriptManager ID="ScriptManager1" runat="server">
i got the idea from here: http://www.vijaykodali.com/Blog/post/2011/11/06/Make-sure-AjaxControlToolkitPropertiesResourcesNET4resources-was-correctly-embedded.aspx
it specifies the reason for the error as
AjaxControlToolkit’s control load reference refers to the base System.Web.UI.Control method which is present as a part of the ASP.NET AJAX Libraries and those libraries are referenced only when the ScriptManager is referenced in the page.