Unexpected Exception on audio syncronization

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I followed exactly the instructions on point 1 on ​http://josm.openstreetmap.de/wiki/Help/AudioMapping/Synchronization
I dragged the orange play head arrow while holding SHIFT key down, when I released the head I obtained the exception.

Path: josm
URL: http://www.openstreetmap.de/svn/josm
Repository Root: http://www.openstreetmap.de/svn/josm
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Revision: 587
Node Kind: directory
Last Changed Author: framm
Last Changed Rev: 587
Last Changed Date: 2008-03-21 01:24:05 +0100 (Fri, 21 Mar 2008)


java.lang.NullPointerException
	at org.openstreetmap.josm.gui.layer.markerlayer.PlayHeadMarker.synchronize(PlayHeadMarker.java:256)
	at org.openstreetmap.josm.actions.mapmode.PlayHeadDragMode.mouseReleased(PlayHeadDragMode.java:74)
	at java.awt.AWTEventMulticaster.mouseReleased(Unknown Source)
	at java.awt.Component.processMouseEvent(Unknown Source)
	at javax.swing.JComponent.processMouseEvent(Unknown Source)
	at java.awt.Component.processEvent(Unknown Source)
	at java.awt.Container.processEvent(Unknown Source)
	at java.awt.Component.dispatchEventImpl(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(Unknown Source)
	at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
	at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
	at java.awt.Container.dispatchEventImpl(Unknown Source)
	at java.awt.Window.dispatchEventImpl(Unknown Source)
	at java.awt.Component.dispatchEvent(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)

[anonymous]

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