1) You need to go to the bin folder of the application
2) open AjaxControlToolkit.dll.refresh under AjaxControlToolkit.dll
( dll file will have .refresh file)
4) Change the path of the AjaxControlToolkit.dll to full path like in my system I used full path C:\Inetpub\wwwroot\<website>\bin\AjaxControlToolkit.dll
5) Save the file and build your apps , it will work.
