GIFProgressiveDisposalTest throws NPE:

java.lang.NullPointerException
at com.sun.imageio.plugins.common.PaletteBuilder.findPaletteEntry(PaletteBuilder.java:310)
at com.sun.imageio.plugins.common.PaletteBuilder.getIndexColorModel(PaletteBuilder.java:296)
at com.sun.imageio.plugins.common.PaletteBuilder.getIndexedImage(PaletteBuilder.java:145)
at com.sun.imageio.plugins.common.PaletteBuilder.createIndexedImage(PaletteBuilder.java:77)
at com.sun.imageio.plugins.gif.GIFImageWriter.write(GIFImageWriter.java:564)
at com.sun.imageio.plugins.gif.GIFImageWriter.writeToSequence(GIFImageWriter.java:510)
at GIFProgressiveDisposalTest.createAnimatedImage(GIFProgressiveDisposalTest.java:298)
at GIFProgressiveDisposalTest.doTest(GIFProgressiveDisposalTest.java:163)
at javasoft.clientsqe.tonga.AbstractTongaManualTest.initScenario(AbstractTongaManualTest.java:197)
at javasoft.clientsqe.tonga.InstructionsFrame$ButtonHandler.actionPerformed(InstructionsFrame.java:165)
at java.awt.Button.processActionEvent(Button.java:392)
at java.awt.Button.processEvent(Button.java:360)
at java.awt.Component.dispatchEventImpl(Component.java:4653)
at java.awt.Component.dispatchEvent(Component.java:4481)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:648)
at java.awt.EventQueue.access$000(EventQueue.java:84)
at java.awt.EventQueue$1.run(EventQueue.java:607)
at java.awt.EventQueue$1.run(EventQueue.java:605)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:98)
at java.awt.EventQueue$2.run(EventQueue.java:621)
at java.awt.EventQueue$2.run(EventQueue.java:619)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:618)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)