Freezing the Video Background by using State

Hi, I'm trying to freeze the background for my app. I'm not sure if I'm using the correct way or term. Basically, I want to stop the camera from updating once I tap on the screen. 

I'm using this page as a reference. https://developer.vuforia.com/resources/dev-guide/freezing-video-background

However, I'm having a problem. I'm getting an error from running this particular code at line 15. 

        state = Renderer.getInstance().begin( frozenState );

I've noted that this function actually returns void.

void com.qualcomm.vuforia.Renderer.begin

(

State

state )

Marks the beginning of rendering for the given frame. Use this to draw a specific camera frame, rather than the latest available one.

So, naturally, eclipse wouldn't let me run it. So I removed the "state =".

 Renderer.getInstance().begin( frozenState );

And this came out in my LogCat

01-03 00:16:02.624: E/AndroidRuntime(22737): FATAL EXCEPTION: GLThread 233201-03 00:16:02.624: E/AndroidRuntime(22737): java.lang.NullPointerException: Attempt to dereference null QCAR::State01-03 00:16:02.624: E/AndroidRuntime(22737): at com.qualcomm.vuforia.VuforiaJNI.Renderer_begin__SWIG_1(Native Method)01-03 00:16:02.624: E/AndroidRuntime(22737): at com.qualcomm.vuforia.Renderer.begin(Renderer.java:67)01-03 00:16:02.624: E/AndroidRuntime(22737): at com.qualcomm.vuforia.samples.VuforiaSamples.app.ImageTargets.ImageTargetRenderer.renderFrame(ImageTargetRenderer.java:266)01-03 00:16:02.624: E/AndroidRuntime(22737): at com.qualcomm.vuforia.samples.VuforiaSamples.app.ImageTargets.ImageTargetRenderer.onDrawFrame(ImageTargetRenderer.java:148)01-03 00:16:02.624: E/AndroidRuntime(22737): at android.opengl.GLSurfaceView$GLThread.guardedRun(GLSurfaceView.java:1527)01-03 00:16:02.624: E/AndroidRuntime(22737): at android.opengl.GLSurfaceView$GLThread.run(GLSurfaceView.java:1244)  I'm not sure what is the problem here. Is it something to do with a Null Pointer? But I've checked the "frozenState" before I begin() it. It's not Null.