Heute wurde ich aktualisiertNetbeans 6.8 zu neuNetbeans 7.4 undJDK 1.7.0 zu1.7.0_45 Wenn ich mein vorheriges Projekt auf neu öffneNetbeans Ausführungsysnthetica look and feel funktioniert nicht :( sonst funktioniert alles einwandfrei :)

try {
UIManager.setLookAndFeel(new SyntheticaBlackStarLookAndFeel());                  

new frm_login().setVisible(true);
    } catch (Exception e) {
        e.printStackTrace();
    }

Das ist der Fehler:

Exception in thread "main" java.lang.NoClassDefFoundError: sun/swing/plaf/synth/SynthUI
at de.javasoft.plaf.synthetica.SyntheticaDefaultLookup.getDefault(SyntheticaDefaultLookup.java:84)
at sun.swing.DefaultLookup.get(DefaultLookup.java:125)
at javax.swing.plaf.basic.BasicButtonListener.getInputMap(BasicButtonListener.java:119)
at javax.swing.plaf.basic.BasicButtonListener.installKeyboardActions(BasicButtonListener.java:95)
at javax.swing.plaf.basic.BasicButtonUI.installKeyboardActions(BasicButtonUI.java:138)
at javax.swing.plaf.basic.BasicButtonUI.installUI(BasicButtonUI.java:90)
at javax.swing.JComponent.setUI(JComponent.java:664)
at javax.swing.AbstractButton.setUI(AbstractButton.java:1807)
at javax.swing.JButton.updateUI(JButton.java:146)
at javax.swing.AbstractButton.init(AbstractButton.java:2172)
at javax.swing.JButton.<init>(JButton.java:136)
at javax.swing.JButton.<init>(JButton.java:90)
at de.javasoft.plaf.synthetica.SyntheticaLookAndFeel.installCompatibilityDefaults(SyntheticaLookAndFeel.java:553)
at de.javasoft.plaf.synthetica.SyntheticaLookAndFeel.access$4(SyntheticaLookAndFeel.java:405)
at de.javasoft.plaf.synthetica.SyntheticaLookAndFeel$2.propertyChange(SyntheticaLookAndFeel.java:313)
at java.beans.PropertyChangeSupport.fire(PropertyChangeSupport.java:335)
at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:327)
at javax.swing.event.SwingPropertyChangeSupport.firePropertyChange(SwingPropertyChangeSupport.java:92)
at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:263)
at javax.swing.UIManager.setLookAndFeel(UIManager.java:545)
at javaapplication1.JavaApplication1.main(JavaApplication1.java:27)
Caused by: java.lang.ClassNotFoundException: sun.swing.plaf.synth.SynthUI
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
... 21 more
Java Result: 1

Was ist der Grund dafür? Wie löse ich das?

Danke im Voraus !