Jar: Could not find the main class <> Program will exit

Blerow

On a construit un Jar et puis voilà l'erreur qui surgit:

Could not find the main class: Blerow. Program will exit.

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Logg er

       at Blerow.Blerow.<clinit>(Blerow.java:36)

Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Logger

       at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
       at java.security.AccessController.doPrivileged(Native Method)
       at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
       at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
       ... 1 more

Could not find the main class: Blerow.Blerow. Program will exit.

vérifier, dans Eclipse, que lors de l'export du jar l option Extract required librairies

.... est bien selectionnée