.Net and SAP web service issue

Hi,

We have created a web service in the XI using soap adapter and we are accessing the web service using .net client (with WSE 2.0 API). but the web service gives following SOAP fault message

http://sap.com/xi/WebService/xi2.0">

<context>XIAdapter</context>

<code>MalformedMessageException</code>

<text><![CDATA[

expecting end tag: Security, but found Timestamp at state 1; nested exception caused by:

com.sap.aii.messaging.util.XMLScanException: expecting end tag: Security, but found Timestamp at state 1

at com.sap.aii.messaging.util.XMLMarshallableObject.unmarshal(XMLMarshallableObject.java:201)

at com.sap.aii.messaging.mo.Message.reparseRootDocument(Message.java:934)

at com.sap.aii.messaging.net.MIMEInputSource.readSOAPPart(MIMEInputSource.java:598)

at com.sap.aii.messaging.net.MIMEInputSource.decodePart(MIMEInputSource.java:590)

at com.sap.aii.messaging.net.MIMEInputSource.readBody(MIMEInputSource.java:358)

at com.sap.aii.messaging.net.MIMEServletInputSource.parse(MIMEServletInputSource.java:58)

at com.sap.aii.af.mp.soap.web.MessageServlet.doPost(MessageServlet.java:359)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:760)

at javax.servlet.http.HttpServlet.service(HttpServlet.java:853)

at com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl.runServlet(HttpHandlerImpl.java:390)

at com.sap.engine.services.servlets_jsp.server.HttpHandlerImpl.handleRequest(HttpHandlerImpl.java:264)

at com.sap.engine.services.httpserver.server.RequestAnalizer.startServlet(RequestAnalizer.java:347)

at com.sap.engine.services.httpserver.server.RequestAnalizer.startServlet(RequestAnalizer.java:325)

at com.sap.engine.services.httpserver.server.RequestAnalizer.invokeWebContainer(RequestAnalizer.java:887)

at com.sap.engine.services.httpserver.server.RequestAnalizer.handle(RequestAnalizer.java:241)

at com.sap.engine.services.httpserver.server.Client.handle(Client.java:92)

at com.sap.engine.services.httpserver.server.Processor.request(Processor.java:148)

at com.sap.engine.core.service630.context.cluster.session.ApplicationSessionMessageListener.process(ApplicationSessionMessageListener.java:33)

at com.sap.engine.core.cluster.impl6.session.MessageRunner.run(MessageRunner.java:41)

at com.sap.engine.core.thread.impl3.ActionObject.run(ActionObject.java:37)

at java.security.AccessController.doPrivileged(Native Method)

at com.sap.engine.core.thread.impl3.SingleThread.execute(SingleThread.java:95)

at com.sap.engine.core.thread.impl3.SingleThread.run(SingleThread.java:160)

]]></text>

</s:SystemError>

weather it has to do any thing with compatibilty between them.

any help will be usefull.