Bukkit

What steps will reproduce the problem?
1.Start the server
2.
3.

What is the expected output? What do you see instead?

In the console: [12:24:11] [Server thread/ERROR]: Could not load 'plugins\ModeStaff.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: Cannot find main class `fr.TookieP.ModeStaff.Main'
    at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:66) ~[server.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131) ~[server.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:329) ~[server.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251) [server.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugins(CraftServer.java:292) [server.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.DedicatedServer.init(DedicatedServer.java:198) [server.jar:git-Spigot-5f38d38-18fbb24]
    at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:525) [server.jar:git-Spigot-5f38d38-18fbb24]
    at java.lang.Thread.run(Unknown Source) [?:1.8.0_51]
Caused by: java.lang.ClassNotFoundException: fr.TookieP.ModeStaff.Main
    at java.net.URLClassLoader.findClass(Unknown Source) ~[?:1.8.0_51]
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:101) ~[server.jar:git-Spigot-5f38d38-18fbb24]
    at org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:86) ~[server.jar:git-Spigot-5f38d38-18fbb24]
    at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_51]
    at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_51]
    at java.lang.Class.forName0(Native Method) ~[?:1.8.0_51]
    at java.lang.Class.forName(Unknown Source) ~[?:1.8.0_51]
    at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64) ~[server.jar:git-Spigot-5f38d38-18fbb24]
    ... 7 more

What version of the product are you using?

Spigot: Latest
Plugin: Latest

Do you have an error log of what happened?

Yeah, Up

Please provide any additional information below.

In the /plugins no is displayed