How to correctly set Icon for Custom Service Task in BRMS / BPM?

Issue

• After following the standard process of creating a task including adding a custom icon to the work item, the UI doesn't let me drag the service task.
  The server log shows the exception below:

2013-05-08 14:39:03,102 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/designer].[StencilSetServiceServlet]] (http-0.0.0.0-8080-4) Servlet.service() for servlet StencilSetServiceServlet threw exception
java.lang.IllegalArgumentException: java.io.FileNotFoundException: /opt/csc/brms/jboss-as/server/default/deploy/designer.war/stencilsets/bpmn2.0jbpm/view/activity/workitems/Log.svg (No such file or directory)
        at org.jbpm.designer.web.stencilset.impl.LocalStencilSetImpl.getResourceContents(LocalStencilSetImpl.java:46)
        at org.jbpm.designer.web.stencilset.impl.StencilSetServiceServlet.doGet(StencilSetServiceServlet.java:89)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
        ...

• After setting icon in BPM 6, the customer service task still has default icon displayed.
  • I try to adjust my custom workitem icon but it's seems not working. I reference my icon at workitem registration but they still show with default icon.I try to put the icon in business-central.war\org.kie.workbench.KIEWebapp\defaults But it's not working.