UpdateManager

I cant update the opmanager build number from 8030 to 8720, i get this error:

Exception in thread "main" java.awt.HeadlessException:
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
    at java.awt.GraphicsEnvironment.checkHeadless(Unknown Source)
    at java.awt.Window.<init>(Unknown Source)
    at java.awt.Frame.<init>(Unknown Source)
    at java.awt.Frame.<init>(Unknown Source)
    at javax.swing.JFrame.<init>(Unknown Source)
    at com.adventnet.tools.update.installer.UpdateManagerUI.<init>(UpdateManagerUI.java:1051)
    at com.adventnet.tools.update.installer.UpdateManager.init(UpdateManager.java:123)
    at com.adventnet.tools.update.installer.UpdateManager.main(UpdateManager.java:354)

Please anyone could help me.

best regards.