Problem invoking the DemoRequestFilter

I Replaced the listener configuration in the demo-listener.xml with the following config

 <tns:listener id="DemoListener" listenerClass="com.eviware.soapui.support.scripting.listeners.ScriptRequestFilter"
  groovyClass="soapui.demo.DemoRequestFilter" listenerInterface="com.eviware.soapui.impl.wsdl.submit.RequestFilter"/> 

, and my DemorequestFilter.groovy class in the folder \soapUI-Pro-3.5.1\bin\scripts\soapui\demo is as below .

package soapui.demo;

import com.eviware.soapui.impl.wsdl.WsdlRequest;
import com.eviware.soapui.impl.wsdl.submit.RequestFilter;
import com.eviware.soapui.impl.wsdl.submit.transports.http.BaseHttpRequestTransport;
import com.eviware.soapui.model.iface.Request;
import com.eviware.soapui.model.iface.Response;
import com.eviware.soapui.model.iface.SubmitContext;
import com.eviware.soapui.support.xml.XmlUtils;

public class DemoRequestFilter implements RequestFilter
{
 @Override
 public void afterRequest(SubmitContext arg0, Request arg1)
 {
  // TODO Auto-generated method stub

 }

 @Override
 public void filterRequest(SubmitContext arg0, Request arg1)
 {
  // TODO Auto-generated method stub

 }

 public void afterRequest( SubmitContext context, Response response )
 {}

 public void filterRequest( SubmitContext context, WsdlRequest wsdlRequest )
 {
 
  log.info "In demo request filter"
  System.out.println( "****running demofilter******" );
 }
}

My DemoRequestFilter class is not getting invoked, I dont see the "In demo request filter" message in my soapui.log. Any insights please. Thanks in advance!!!