Error consuming web service

Hello,
I am getting the following SOAP fault while consuming a client web service:

<?xml version="1.0" encoding="UTF-8"?>

<SOAP-ENV:Envelope xmlns:SOAP-ENV=“http://schemas.xmlsoap.org/soap/envelope/” xmlns:SOAP-ENC=“http://schemas.xmlsoap.org/soap/encoding/” xmlns:xsd=“http://www.w3.org/2001/XMLSchema” xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance”>
<SOAP-ENV:Header xmlns:SOAP-ENV=“http://schemas.xmlsoap.org/soap/envelope/”></SOAP-ENV:Header>SOAP-ENV:BodySOAP-ENV:Fault
SOAP-ENV:Client
[ISS.0088.9251] JAX-RPC Handler failed to process the message
http://schemas.xmlsoap.org/soap/actor/next
<webM:detailEntry xmlns:webM=“http://www.webMethods.com/2001/10/soap/encoding” xmlns:xml=“http://www.w3.org/XML/1998/namespace”>
<webM:message xml:lang="">com.webmethods.ws.security.SecurityException: WS Security processing failed : Unable to resolve private key for signing or decrypting the message</webM:message>
</webM:detailEntry>
</SOAP-ENV:Fault></SOAP-ENV:Body>
</SOAP-ENV:Envelope>

I am using security policy Sign_Auth_for_consumer.xml. Our client provided us a certificate to validate the connection to their server and another certificate for the web service. I added both in the definition of the web service end point.
Even though I am getting that SOAP response I am not sure of is if I am hitting their web service or that message comes from our IS.
Any help is appreciated.
Thank you.

Check if the private key path mentioned in the endpoint is correct.