javafx applet cannot launch if signed JNLP file is used

testcase: http://javaweb.sfbay.sun.com/~ngthomas/javafx/customcursor/CustomCursorsDemo.html

java.lang.ClassNotFoundException: com.sun.javafx.runtime.adapter.Applet because the class is not signed.
   at sun.plugin2.applet.Plugin2ClassLoader.newClassNotFoundException(Unknown Source)
   at sun.plugin2.applet.Plugin2ClassLoader$2.run(Unknown Source)
   at java.security.AccessController.doPrivileged(Native Method)
   at sun.plugin2.applet.Plugin2ClassLoader.findClassHelper(Unknown Source)
   at sun.plugin2.applet.JNLP2ClassLoader.findClass(Unknown Source)
   at java.lang.ClassLoader.loadClass(Unknown Source)
   at java.lang.ClassLoader.loadClass(Unknown Source)
   at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
   at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
   at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
   at java.lang.Thread.run(Unknown Source)
Exception: java.lang.ClassNotFoundException: com.sun.javafx.runtime.adapter.Applet because the class is not signed.