ajax error

I have ajax control toolkit in bin folder ,i have win 7 inmy system but still i m getting this error ..please help

Could not load file or assembly 'AjaxControlToolkit' or one of its dependencies. The parameter is incorrect. (Exception from HRESULT: 0x80070057 (E_INVALIDARG))

Hello,

Is it possible that you have another version of the AjaxControlToolkit in your Global Assembly Cache.

Does this happen if you create a brand new application and only reference the DLL?

Gary