NTLM Authentication - WCF REST

Hi,

We are having problems connecting to our Wcf Rest Service that uses NTLM (Windows) authentication, hosted on IIS7.5.

Every time we connect we get via SoapUI we get a 401 - Unauthorized: Access is denied due to invalid credentials

The credentials are fine as we can connect fine through our application(c#) using exactly the same credentials.

We have entered the credentials in the Request Properties dialogue, with correct domain\username and password, and the authentication type is set to NTLM/Kerberos.
Also, we have checked the Authenticate Preemptively option in Preferences-->HTTP Settings

Any help or ideas would be appreciated.

soapUI 4.5.2

Thanks