Caused by: org.apache.ws.security.WSSecurityException: General security error (WSEncryptBody/WSSignE nvelope: Element to encrypt/sign not found: {http://ws.apache.org/axis2}args0)

Here I am trying to run a multiplication service in which I pass 2 parameters. In these two parameters I am trying to encrypt and sign only single element. For this I am using <SignedElements> and <EncryptedElements> assertions. I am calling the service using Client stub in which the namaspace generated is xmlns:ns1="http://ws.apache.org/axis2". I amt trying to use Xpath for that element as <sp:XPath>/soapenv:Envelope/soapenv:Body/ns1:mul/ns1:args0</sp:XPath> where soapenv is xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope">.
When this got error i changed Xpath to:
<sp:XPath>descendant::ns1:args0</sp:XPath>
But i am getting an error which is
Caused by: org.apache.ws.security.WSSecurityException: General security error (WSEncryptBody/WSSignE nvelope: Element to encrypt/sign not found:

args0)

Abhinav
Abhinav Mishra
Exception in thread "main" org.apache.axis2.AxisFault: Error during encryption
at org.apache.rampart.handler.RampartSender.invoke(RampartSender.java:70)
at org.apache.axis2.engine.Phase.invoke(Phase.java:318)
at org.apache.axis2.engine.AxisEngine.invoke(AxisEngine.java:251)
at org.apache.axis2.engine.AxisEngine.send(AxisEngine.java:416)
at org.apache.axis2.description.OutInAxisOperationClient.send(OutInAxisOperation.java:402)
at org.apache.axis2.description.OutInAxisOperationClient.executeImpl(OutInAxisOperation.java
:229)
at org.apache.axis2.client.OperationClient.execute(OperationClient.java:165)
at org.apache.ws.axis2.Multiplication4Stub.mul(Multiplication4Stub.java:187)
at org.apache.ws.axis2.Client.main(Client.java:38)
Caused by: org.apache.rampart.RampartException: Error during encryption
at org.apache.rampart.builder.AsymmetricBindingBuilder.doSignBeforeEncrypt(AsymmetricBinding
Builder.java:544)
at org.apache.rampart.builder.AsymmetricBindingBuilder.build(AsymmetricBindingBuilder.java:9
3)
at org.apache.rampart.MessageBuilder.build(MessageBuilder.java:147)
at org.apache.rampart.handler.RampartSender.invoke(RampartSender.java:64)
... 8 more
Caused by: org.apache.ws.security.WSSecurityException: General security error (WSEncryptBody/WSSignE
nvelope: Element to encrypt/sign not found:

args0)
at org.apache.ws.security.message.WSSecEncrypt.doEncryption(WSSecEncrypt.java:496)
at org.apache.ws.security.message.WSSecEncrypt.doEncryption(WSSecEncrypt.java:454)
at org.apache.ws.security.message.WSSecEncrypt.encryptForInternalRef(WSSecEncrypt.java:351)
at org.apache.rampart.builder.AsymmetricBindingBuilder.doSignBeforeEncrypt(AsymmetricBinding
Builder.java:530)
... 11 more

So,please help me to solve this issue.
Here i am attaching my code and services.xml file.
Thanks in advance!!!