Problem with decryption

[Fred Victa]

I have a web service written in Java and I have a client who has a web service written in .NET. We are using x509 security certificates. When my client sends a message to my service, he gets an error that says, "General security error (Unexpected number of X509Data: for decryption (KeyId))" . I checked with my client and he is using the correct certificates to sign and encrypt his messages and I'm using the correct certificates to decrypt messages and verify signatures. Below is the error message that he was getting. What could be the problem?

javax.xml.soap.SOAPException: General security error (Unexpected number of X509Data: for decryption (KeyId))
at org.apache.axis2.saaj.SOAPConnectionImpl.handleSOAPMessage(SOAPConnectionImpl.java:193)
at org.apache.axis2.saaj.SOAPConnectionImpl.call(SOAPConnectionImpl.java:129)
at com.thehartford.savi.impl.util.WSClient.sendSOAPRequest(WSClient.java:110)
at com.thehartford.savi.impl.util.WSClient.main(WSClient.java:63)
Caused by: org.apache.axis2.AxisFault: General security error (Unexpected number of X509Data: for decryption (KeyId))
at org.apache.axis2.util.Utils.getInboundFaultFromMessageContext(Utils.java:486)
at org.apache.axis2.description.OutInAxisOperationClient.handleResponse(OutInAxisOperation.java:343)
at org.apache.axis2.description.OutInAxisOperationClient.send(OutInAxisOperation.java:389)
at org.apache.axis2.description.OutInAxisOperationClient.executeImpl(OutInAxisOperation.java:211)RESPONE null

at org.apache.axis2.client.OperationClient.execute(OperationClient.java:163)
at org.apache.axis2.saaj.SOAPConnectionImpl.handleSOAPMessage(SOAPConnectionImpl.java:187)
... 3 more