Help: Getting an error message on running a test step.

Hi,

I am a begineer to SOAP UI PRO. Please help me in sorting an issue where if i run a test step, I am getting an error message "SOAP RESPONSE-Valid", "Not SOAP Fault- Failed" and Response is a SOAP Fault. Whats this error message?
In the output xml result: I am getting this result:

<SOAP-ENV:Body>

<SOAP-ENV:Fault>

<faultcode>SOAP-ENV:Client</faultcode>

<faultstring xml:lang="en">No WS-Security header found</faultstring>

</SOAP-ENV:Fault>

</SOAP-ENV:Body>