display list with solid sphere in error

hi guys

I’m trying to understand how use the display list and i have create a very easy code just to draw a sphere

this is my code in the init


public void init(GLAutoDrawable drawable) {

                ............
                ............

		sp = gl.glGenLists(1);
		gl.glNewList(sp, GL2.GL_COMPILE);
		glut.glutSolidSphere (0.4, 16, 16);
		gl.glEndList();
}

bat during the execution of glut.glutSolidSphere (0.4, 16, 16); i take this exception


Exception in thread "Timer-0" java.lang.RuntimeException: java.lang.NullPointerException
	at jogamp.common.awt.AWTEDTExecutor.invoke(AWTEDTExecutor.java:58)
	at jogamp.opengl.awt.AWTThreadingPlugin.invokeOnOpenGLThread(AWTThreadingPlugin.java:103)
	at jogamp.opengl.ThreadingImpl.invokeOnOpenGLThread(ThreadingImpl.java:206)
	at javax.media.opengl.Threading.invokeOnOpenGLThread(Threading.java:172)
	at javax.media.opengl.Threading.invoke(Threading.java:191)
	at javax.media.opengl.awt.GLCanvas.display(GLCanvas.java:428)
	at com.jogamp.opengl.util.AWTAnimatorImpl.display(AWTAnimatorImpl.java:74)
	at com.jogamp.opengl.util.AnimatorBase.display(AnimatorBase.java:142)
	at com.jogamp.opengl.util.FPSAnimator$1.run(FPSAnimator.java:128)
	at java.util.TimerThread.mainLoop(Timer.java:512)
	at java.util.TimerThread.run(Timer.java:462)
Caused by: java.lang.NullPointerException
	at it.spaghettisource.cap6.exn6p3.init(exn6p3.java:78)
	at jogamp.opengl.GLDrawableHelper.init(GLDrawableHelper.java:201)
	at jogamp.opengl.GLDrawableHelper.init(GLDrawableHelper.java:222)
	at javax.media.opengl.awt.GLCanvas$6.run(GLCanvas.java:926)
	at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:521)
	at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:462)
	at javax.media.opengl.awt.GLCanvas$9.run(GLCanvas.java:964)
	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:199)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:646)
	at java.awt.EventQueue.access$000(EventQueue.java:84)
	at java.awt.EventQueue$1.run(EventQueue.java:607)
	at java.awt.EventQueue$1.run(EventQueue.java:605)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:616)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)

can i use the glut function in the display list?
or i have to activate same flag that i forgot?

thanks