I got this exception when saving a service.

java.lang.NullPointerException
	at impl.owls.process.BindingImpl.setValue(BindingImpl.java:75)
	at impl.owls.process.PerformImpl.addBinding(PerformImpl.java:34)
	at
org.mindswap.composer.ServiceComposer.createSequenceProcess(ServiceComposer.java:1443)
	at
org.mindswap.composer.ServiceComposer.createSequenceService(ServiceComposer.java:1241)
	at
org.mindswap.composer.ServiceComposer.saveCompositionToFile(ServiceComposer.java:1207)
	at
org.mindswap.composer.SaveCompositionDialog$1.actionPerformed(SaveCompositionDialog.java:59)
	at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1786)
	at
javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:1839)
	at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
	at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
	at
javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:245)
	at java.awt.Component.processMouseEvent(Component.java:5100)
	at java.awt.Component.processEvent(Component.java:4897)
	at java.awt.Container.processEvent(Container.java:1569)
	at java.awt.Component.dispatchEventImpl(Component.java:3615)
	at java.awt.Container.dispatchEventImpl(Container.java:1627)
	at java.awt.Component.dispatchEvent(Component.java:3477)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3483)
	at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3198)
	at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3128)
	at java.awt.Container.dispatchEventImpl(Container.java:1613)
	at java.awt.Window.dispatchEventImpl(Window.java:1606)
	at java.awt.Component.dispatchEvent(Component.java:3477)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:456)
	at
java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
	at
java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)
ERROR: Cannot save composition to file: java.lang.NullPointerException