Hello everyone i need some help with an error that occured while i'm trying to install GLGRAPICS.

I followed all the instructions and placed the unfolding library and GLGRAPHICS library into my processing library folder and when i select the add library option it doesn't reflect itself as an option. So i tried with the Add file option and this error popped up:

Exception in thread "Animation Thread" java.lang.NoClassDefFoundError: processing/opengl/PGraphicsOpenGL$ImageCache
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2389)
    at java.lang.Class.getConstructor0(Class.java:2699)
    at java.lang.Class.getConstructor(Class.java:1657)
    at processing.core.PApplet.makeGraphics(PApplet.java:1735)
    at processing.core.PApplet.size(PApplet.java:1588)
    at processing.core.PApplet.size(PApplet.java:1559)
    at sketch_130124c.setup(sketch_130124c.java:52)
    at processing.core.PApplet.handleDraw(PApplet.java:2103)
    at processing.core.PGraphicsJava2D.requestDraw(PGraphicsJava2D.java:190)
    at processing.core.PApplet.run(PApplet.java:2006)
    at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.ClassNotFoundException: processing.opengl.PGraphicsOpenGL$ImageCache
    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)
    ... 12 more


Can anyone please assist me? I need to solve this for my final year project. Help would be greatly appreciated!!