https://community.jboss.org/servlet/JiveServlet/downloadImage/2-756398-19306/450-277/JBoss+Guvnor.png
From my experience , you should have an image which has the filename "processId-image" in the process package (See the attachment above) . This image can be generated automatically by opening the process in the designer , and then click the "PNG" button in the bottom toolbar
