Copy testcases cause NPE

Hi,

when I copy testcase from one project to other I got this exception:
I am using soap ui pro 4.5.1

Tue Feb 05 14:50:02 CET 2013:ERROR:java.lang.NullPointerException
java.lang.NullPointerException
at net.infonode.properties.propertymap.PropertyMapManager.addMapChanges(Unknown Source)
at net.infonode.properties.propertymap.PropertyMapImpl$1.signalEmitted(Unknown Source)
at net.infonode.util.signal.Signal.emit(Unknown Source)
at net.infonode.util.collection.notifymap.AbstractConstChangeNotifyMap.fireEntriesChanged(Unknown Source)
at net.infonode.properties.propertymap.PropertyMapImpl$PropertyObjectMap.fireEntriesChanged(Unknown Source)
at net.infonode.properties.propertymap.PropertyMapImpl$PropertyObjectMap.signalEmitted(Unknown Source)
at net.infonode.util.signal.Signal.emit(Unknown Source)
at net.infonode.util.collection.notifymap.AbstractConstChangeNotifyMap.fireEntriesChanged(Unknown Source)
at net.infonode.util.collection.notifymap.ConstChangeNotifyVectorMap.addMap(Unknown Source)
at net.infonode.properties.propertymap.PropertyMapImpl.addSuperMap(Unknown Source)
at net.infonode.properties.propertymap.PropertyMapImpl.addSuperMap(Unknown Source)
at net.infonode.tabbedpanel.TabbedPanelProperties.addSuperObject(Unknown Source)
at com.eviware.soapui.support.components.JInspectorPanelImplPro$2.run(SourceFile:155)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)