Service to service call on same IIS with windows authentication

Hi people i have some issue like this:

I have two WCF services both with:

<bindings><basicHttpBinding><binding name="basicHttpBinding" /><binding name="SecureBasicBindingConfiguration"><security mode="TransportCredentialOnly"><transport clientCredentialType="Windows" /></security></binding></basicHttpBinding></bindings>

Both WCF services run in a IIS pool with a valid Active Directory user account, the first service calls the second one, if the services run in different IIS, diferent machines there is no problem, now if the services are hosted in the same IIS in the same machine i get error 401 Unauthorized.

Can anybody explain me why and how to solve this ?

Does impersonation or delegation of the first WCF service help if both services run in the same IIS?

Thanks!