Error adding JAR librairy

Hello guys, I'm getting an error while trying to use JDOM with my bukkit plugin :/

What I did:
- I copied the jar file to a created folder "lib" in my project
- I added the jar file to the build path

Error:

Code:

java.lang.NoClassDefFoundError: org/jdom2/input/SAXBuilder
    at me.maestro34.maespgm.map.Map.<init>(Map.java:28)
    at me.maestro34.maespgm.map.MapLoader.load(MapLoader.java:31)
    at me.maestro34.maespgm.MaesPGM.onEnable(MaesPGM.java:35)
    at org.bukkit.plugin.java.JavaPlugin.setEnabled(JavaPlugin.java:315)
    at org.bukkit.plugin.java.JavaPluginLoader.enablePlugin(JavaPluginLoader.java:323)
    at org.bukkit.plugin.SimplePluginManager.enablePlugin(SimplePluginManager.java:416)
    at org.bukkit.craftbukkit.v1_7_R4.CraftServer.loadPlugin(CraftServer.java:461)
    at org.bukkit.craftbukkit.v1_7_R4.CraftServer.enablePlugins(CraftServer.java:395)
    at net.minecraft.server.v1_7_R4.MinecraftServer.n(MinecraftServer.java:362)
    at net.minecraft.server.v1_7_R4.MinecraftServer.g(MinecraftServer.java:336)
    at net.minecraft.server.v1_7_R4.MinecraftServer.a(MinecraftServer.java:292)
    at net.minecraft.server.v1_7_R4.DedicatedServer.init(DedicatedServer.java:189)
    at net.minecraft.server.v1_7_R4.MinecraftServer.run(MinecraftServer.java:446)
    at net.minecraft.server.v1_7_R4.ThreadServerApplication.run(SourceFile:628)
Caused by: java.lang.ClassNotFoundException: org.jdom2.input.SAXBuilder
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:77)
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:62)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    ... 14 more

Can someone help me please ? :/

 

You also have to have the JAR running on your server.

And try using depend in your plugin.yml

 

JDOM is not a bukkit plugin, so, I can't use it like a bukkit plugin and either in depends :/