Server Error in '/' Application.
Could not load file or assembly 'AjaxControlToolkit' or one of its dependencies. The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))
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.IO.FileLoadException: Could not load file or assembly 'AjaxControlToolkit' or one of its dependencies. The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))
'C:\Windows\Microsoft.NET\Framework\v4.0.30319\Temporary ASP.NET Files'
(Yukarıda yazan 'v4.0.30319' kısmını kullanmakta olduğunuz asp.net framework ü ile değiştirmeniz gerekiyor.)