Can't start a libgdx desktop project-Collection of common programming errors

I’m developing an Android application with Libgdx. Everything has gone good so far (I’ve been debugging in the emulator), but I came to a point where I needed to set up a desktop project, so I could test the app faster (so instead of running it on an emulator, I could test it on a desktop app).

I made the setup just as the wiki says, adding the desktop version, and everything has gone good so far, no compiler errors. But when I try to launch the desktop app, I get the following error, without even opening a window:

Exception in thread "main" java.lang.NoClassDefFoundError: com/badlogic/gdx/Net
    at DesktopGame.main(DesktopGame.java:12)
Caused by: java.lang.ClassNotFoundException: com.badlogic.gdx.Net
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)

The line 12 of the DesktopGame.java says:

new LwjglApplication(new UserStart(userID, appDefinitions), "Game", 1024, 600, false);

Where UserStart is the ApplicationListener (with a custom constructor as I needed a couple of parameters, this setup works well on Android). I don’t know why com.badlogic.gdx.Net is not found (and I don’t know why it is looking for it as I’m not using network features).

Does anyone know what could it be? Thanks!