Error 500 while trying to access the web service through ESB SOAP Proxy

Issue

• While accessing a web service via SOAP Proxy we are getting following exception

2011-09-16 13:20:10,896 INFO  [STDOUT] (pool-47-thread-1) Message before calling action on XYZ Service:
2011-09-16 13:20:10,897 INFO  [STDOUT] (pool-47-thread-1) [<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xyz="http://my.company.com/sso/services/xyz">    <soapenv:Header/>   <soapenv:Body>  <xyz:requestDataRequest dienstId="ABC1" ssoKundenNummer="EFGH70">         <dsds:key>TESTKEY</dsds:key>      </xyz:requestDataRequest> </soapenv:Body>
</soapenv:Envelope>
].
2011-09-16 13:20:10,897 WARN  [org.jboss.soa.esb.actions.soap.proxy.SOAPProxy] (pool-47-thread-1) null binding for soapaction ['']; parsing envelope to discover operation...
2011-09-16 13:20:10,906 ERROR [org.jboss.soa.esb.actions.soap.proxy.SOAPProxy] (pool-47-thread-1) null binding for operation [{http://my.company.com/sso/services/xyz}requestDataRequest] in addition to soapaction ['']
2011-09-16 13:20:10,906 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/XYZ].[XYZHttpListener]] (http-10.10.10.10-8080-2) Servlet.service() for servlet XYZHttpListener threw exception
org.jboss.soa.esb.actions.ActionProcessingException: null transport for soapaction [''], operation [{http://my.company.com/sso/services/xyz}requestDataRequest], binding [null]
at org.jboss.soa.esb.actions.soap.proxy.SOAPProxy.process(SOAPProxy.java:355)
at org.jboss.soa.esb.listeners.message.ActionProcessingPipeline.processPipeline(ActionProcessingPipeline.java:649)
at org.jboss.soa.esb.listeners.message.ActionProcessingPipeline.processPipeline(ActionProcessingPipeline.java:603)
at org.jboss.soa.esb.listeners.message.ActionProcessingPipeline.process(ActionProcessingPipeline.java:433)
at org.jboss.soa.esb.listeners.message.MessageAwareListener$TransactionalRunner.run(MessageAwareListener.java:550)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
at java.lang.Thread.run(Thread.java:636)

The jboss-esb.xml file looks like the following

<?xml version="1.0"?>
<jbossesb parameterReloadSecs="5"
xmlns="http://anonsvn.labs.jboss.com/labs/jbossesb/trunk/product/etc/schemas/xml/jbossesb-1.2.0.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://anonsvn.labs.jboss.com/labs/jbossesb/trunk/product/etc/schemas/xml/jbossesb-1.2.0.xsd http://anonsvn.jboss.org/repos/labs/labs/jbossesb/trunk/product/etc/schemas/xml/jbossesb-1.2.0.xsd">
<services>
  <service category="proxies" description="proxies" invmScope="GLOBAL" name="xyzService">
   <listeners>
    <http-gateway name="XYZHttpListener"/>
   </listeners>
   <actions mep="RequestResponse">
    <action class="org.jboss.soa.esb.actions.SystemPrintln" name="print-before">
     <property name="message" value="Message before calling action on XYZ Service"/>
    </action>
    <action class="org.jboss.soa.esb.actions.soap.proxy.SOAPProxy" name="xyzSoapProxy">
     <property name="wsdl" value="classpath:///META-INF/xyz.wsdl"/>
    </action>
   </actions>
  </service>
</services>
</jbossesb>

Service works fine with when we call it directly without proxy, which proves it's up and running. So, what is causing this HTTP 500 Error code in response.