Problem with Calendar Extender

I have the Calendar Extender from the Ajax Control Toolkit installed and running in Project1. I also want to use it in Project 2. I have added the same reference and the same markup code but in Project 2 I get this error.

Server Error in '/' Application.

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. 
  Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

 Exception Details: System.Resources.MissingManifestResourceException: 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.

Source Error: 


 An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.  

Stack Trace: 



[MissingManifestResourceException: 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.]
   System.Resources.ManifestBasedResourceGroveler.HandleResourceStreamMissing(String fileName) +311
   System.Resources.ManifestBasedResourceGroveler.GrovelForResourceSet(CultureInfo culture, Dictionary`2 localResourceSets, Boolean tryParents, Boolean createIfNotExists, StackCrawlMark& stackMark) +993
   System.Resources.ResourceManager.InternalGetResourceSet(CultureInfo requestedCulture, Boolean createIfNotExists, Boolean tryParents, StackCrawlMark& stackMark) +810
   System.Resources.ResourceManager.InternalGetResourceSet(CultureInfo culture, Boolean createIfNotExists, Boolean tryParents) +34
   System.Resources.ResourceManager.GetString(String name, CultureInfo culture) +427
   AjaxControlToolkit.Properties.Resources_NET4.get_E_NoScriptManager() +59
   AjaxControlToolkit.ScriptObjectBuilder.RegisterCssReferences(Control control) +757
   AjaxControlToolkit.ExtenderControlBase.OnLoad(EventArgs e) +62
   System.Web.UI.Control.LoadRecursive() +54
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Control.LoadRecursive() +145
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +772

  


Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.34237  

Can someone suggest a fix? Thanks