NPE in takeScreenshot

When I try to call renderer.takeSnapshot from inside a SimpleCanvasImpl, I am getting the following exception.

Exception in thread "main" java.lang.NullPointerException

        at org.lwjgl.opengl.GL11.glReadPixels(

        at com.jme.renderer.lwjgl.LWJGLRenderer.grabScreenContents(Unknown Source)

        at com.jme.renderer.lwjgl.LWJGLRenderer.takeScreenShot(Unknown Source)

Has anyone else run into this?  I looked at the source for GL11 and it's an interface.  Before I go and reverse engineer the code, does anyone have any helpful hints?


Sorry, I'll search first next time: