HTTPS Without client authentication shows error of Certificate

Hi Experts,

I am trying to develop a SOAP to RFC scenario where in SOAP sender HTTP security level - HTTPS Without Client Authentication is selected.

I have downloaded WSDL from Sender agreement and trying to test web service from SOAPUI.  Now as per my understanding simply placing request to HTTPS:<host>:<port>:XISOAPAdapter/....   with correct user should work and this scenario shouldn't need any certificates.

However in SOAPUI and even in RWB SOAP Sender, I am receiving error that - Client Certificate required.

Any comments on why would it be happening ?    In fact whatever option in HTTP Security level I select, error remains same. In NWA is there any other configuration to be done to make this work ?

Is below understanding right ?

-- >> HTTPS Without client authentication will not need certificate exchange and simply user authentication will do

Thanks..

regards,

Omkar.