Problems with DisguiseCraft and Sentry

Hello,

I've got two problems : firstly, the plugin DisguiseCraft is installed on my server, but doesnt' appear after typing /plugins.
Here are the logs :

[18:09:58] [Server thread/ERROR]: Could not load 'plugins/DisguiseCraft.jar' in folder 'plugins'
org.bukkit.plugin.InvalidPluginException: java.lang.NoClassDefFoundError: net/minecraft/server/v1_8_R2/Packet
at
org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:135)
~[minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
at
org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:329)
~[minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
at
org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251)
[minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
at
org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugins(CraftServer.java:291)
[minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
at
net.minecraft.server.v1_8_R3.DedicatedServer.init(DedicatedServer.java:198)
[minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:528) [minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
at java.lang.Thread.run(Thread.java:745) [?:1.7.0_79]
Caused by: java.lang.NoClassDefFoundError: net/minecraft/server/v1_8_R2/Packet
at java.lang.Class.forName0(Native Method) ~[?:1.7.0_79]
at java.lang.Class.forName(Class.java:274) ~[?:1.7.0_79]
at
org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64)
~[minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
at
org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131)
~[minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
... 6 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.server.v1_8_R2.Packet
at
org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:91)
~[minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
at
org.bukkit.plugin.java.PluginClassLoader.findClass(PluginClassLoader.java:86)
~[minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
at java.lang.ClassLoader.loadClass(ClassLoader.java:425) ~[?:1.7.0_79]
at java.lang.ClassLoader.loadClass(ClassLoader.java:358) ~[?:1.7.0_79]
at java.lang.Class.forName0(Native Method) ~[?:1.7.0_79]
at java.lang.Class.forName(Class.java:274) ~[?:1.7.0_79]
at
org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:64)
~[minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
at
org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131)
~[minecraft_server.jar:git-Spigot-f928e7a-e91aed8]
... 6 more

My second problem is about Sentry : when I want to install it, the only available version is a .zip file, whereas I'm looking for a .jar... Moreover, I don't know if the latest version of Sentry is compatible with the latest one of Citizens, but I need bth of them to create a boss... What should I do ?

Thanks for supporting !

About Sentry, there is another problem : it appears on the website's plugin list, but doesn't appear in game after typing /plugins... It seems not to be recognized, what should I do ? Do I have to install "Citizens for CH 1.7.9-RO.1" so that they can work together ? I'm lost...

It must not be compatible : the version of Spigot is 1.8.7, whereas Sentry's version is 1.7.9. But I already use the newest version of Sentry, and I want to develop a 1.8 server : does it mean I won't be able to use Sentry ? I've already seen somme 1.8 servers where Sentry is used... Is it possible to use Sentry anyway ?

I guess I won't be able to develop my server in 1.8 because of this... It must be possible to create a 1.7.X server which allows 1.8 clients to connect on it, how can I do it on Aternos please ?

Okay, finally is there any solution to develop a 1.8 server with Citizens and Sentry to make them work together ?

What do you mean by the "server hosting service" ? Does it implie I have not to use Aternos servers anymore to fix the problem ?
Sorry for my misunderstanding, I'm not English

Bad luck... Thanks for supporting anyway !