This app gives error to me. java.lang.UnsupportedClassVersionError: greenfoot/export/GreenfootScenarioViewer : Unsupported major.minor version 51.0 at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631) at java.lang.ClassLoader.defineClass(ClassLoader.java:615) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) at java.net.URLClassLoader.defineClass(URLClassLoader.java:283) at java.net.URLClassLoader.defineClass(URLClassLoader.java:217) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at sun.plugin2.applet.Plugin2ClassLoader.defineClassHelper(Plugin2ClassLoader.java:1014) at sun.plugin2.applet.Plugin2ClassLoader.access$100(Plugin2ClassLoader.java:69) at sun.plugin2.applet.Plugin2ClassLoader$2.run(Plugin2ClassLoader.java:991) at java.security.AccessController.doPrivileged(Native Method) at sun.plugin2.applet.Plugin2ClassLoader.findClassHelper(Plugin2ClassLoader.java:955) at sun.plugin2.applet.Applet2ClassLoader.findClass(Applet2ClassLoader.java:134) at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Plugin2ClassLoader.java:250) at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Plugin2ClassLoader.java:180) at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Plugin2ClassLoader.java:161) at java.lang.ClassLoader.loadClass(ClassLoader.java:247) at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Plugin2ClassLoader.java:675) at sun.plugin2.applet.Plugin2Manager.createApplet(Plugin2Manager.java:3025) at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Plugin2Manager.java:1498) at java.lang.Thread.run(Thread.java:662) Exception: java.lang.UnsupportedClassVersionError: greenfoot/export/GreenfootScenarioViewer : Unsupported major.minor version 51.0