I get this error when testing headless

moberg@cm:~/opt/Spine$ unset DISPLAY
moberg@cm:~/opt/Spine$ ./Spine.sh
Spine Launcher 3.0.05
Linux amd64 3.13.0-74-generic
Java 1.7.0_06 Esoteric Software
64-bit Server VM
An unexpected error has occurred:
java.awt.HeadlessException:
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
at java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:207)
at java.awt.Window.<init>(Window.java:535)
at java.awt.Frame.<init>(Frame.java:420)
at javax.swing.JFrame.<init>(JFrame.java:224)
at tzax.s.<init>(SourceFile:319)
at com.esotericsoftware.spine.editor.launcher.Launcher.<init>(SourceFile:319)
at tzax.l.run(SourceFile:1554)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:711)
at java.awt.EventQueue.access$000(EventQueue.java:104)
at java.awt.EventQueue$3.run(EventQueue.java:672)
at java.awt.EventQueue$3.run(EventQueue.java:670)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:681)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)
java.awt.HeadlessException:
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
at java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:207)
at java.awt.Window.<init>(Window.java:535)
at java.awt.Frame.<init>(Frame.java:420)
at java.awt.Frame.<init>(Frame.java:385)
at javax.swing.SwingUtilities$SharedOwnerFrame.<init>(SwingUtilities.java:1759)
at javax.swing.SwingUtilities.getSharedOwnerFrame(SwingUtilities.java:1834)
at javax.swing.JOptionPane.getRootFrame(JOptionPane.java:1697)
at javax.swing.JOptionPane.showOptionDialog(JOptionPane.java:863)
at tzax.C.run(SourceFile:88)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:251)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:711)
at java.awt.EventQueue.access$000(EventQueue.java:104)
at java.awt.EventQueue$3.run(EventQueue.java:672)
at java.awt.EventQueue$3.run(EventQueue.java:670)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:681)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:244)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:163)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:147)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:139)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:97)
moberg@cm:~/opt/Spine$