MSCRM4: SoapHeaderAuthenticationProvider showing in custom page

Recently i try to deploy my custom page into a fresh new installed CRM Titan server.
I hit the SoapHeaderAuthenticationProvider error,message:-

'Microsoft.Crm.WebServices.Crm2007.MultipleOrganizationSoapHeaderAuthenticationProvider,
Microsoft.Crm.WebServices, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=31bf3856ad364e35' doesn't exist.
Parameter name:
Microsoft.Crm.WebServices.Crm2007.MultipleOrganizationSoapHeaderAuthenticationProvider,
Microsoft.Crm.WebServices, Version=4.0.0.0, Culture=neutral,
PublicKeyToken=31bf3856ad364e35

Solution:
Error is cause by one of the MSCRM DLL "Microsoft.Crm.WebServices.dll" does not register under GAC.
Just Drag the DLL to GAC folder solved the problem.