AndEngine physicsWorld crash the game

Question

how the title says, if i try to use physicsWorld the game will close when he read it. i use GLES_2 AnchorCenter and the codes looks as follow:

@Override
public void createScene()
{
    createBackground();
    createHUD();
    createPhysics();
}

private void createPhysics()
{
    physicsWorld = new FixedStepPhysicsWorld(60, new Vector2(0, -17), false);
    this.registerUpdateHandler(physicsWorld);
}

If i use createPhysics(); as comment or delete it so the gamescene works. i must include anything for this? i tryed already few things:

1. change build.gradle

   jni.srcDirs = [] jniLibs.srcDir 'libs'

Tryed too: jniLibs.srcDir 'src/main/jniLibs'

dont know if there a different ^^

2. check if the scr folder is a Source folder, all files have a C on the front so should be a Source folder. correct me if iam wrong ^^

i hope thats enought informations ^^ if not let me know :P