6 viewports only one render the scene

Hi!
I have this code that create a Cubemap from six viewports.The rootNode scene has attached to the viewports, but only the top viewport shows the scene:

The code:

[java]public class HelloReflection extends SimpleApplication{

DirectionalLight sun;
Material mirror_mat;

public static void main(String[] args)
{
    HelloReflection app = new HelloReflection();
    app.start();
}

public void simpleInitApp()
{
    initCamera();
    rootNode.attachChild(initSkyBox());
    initLight();
    initMaterial();
    initGeometry();
}

protected void initCamera()
{
    flyCam.setMoveSpeed(50);
}

protected Spatial initSkyBox()
{
   return SkyFactory.createSky(
            assetManager, 
            "Textures/Sky/Bright/BrightSky.dds", 
            false);
}

protected void initLight()
{
    sun = new DirectionalLight();
    sun.setDirection(new Vector3f(1,0,-2).normalizeLocal());
    sun.setColor(ColorRGBA.White);
    rootNode.addLight(sun);
}    

protected void initMaterial()
{
    mirror_mat = new Material(assetManager,
             "Shaders/Reflection/Reflection.j3md");
    
    Camera top_cam = new Camera(512,512);
    top_cam.setFrustumPerspective(45f, 1f, 1f, 1000f);
    top_cam.setLocation(new Vector3f(0f, 5f, 0f));
    top_cam.lookAtDirection(new Vector3f(0,1,0), Vector3f.UNIT_Y);
    
    Camera bottom_cam = new Camera(512,512);
    top_cam.setFrustumPerspective(45f, 1f, 1f, 1000f);
    top_cam.setLocation(new Vector3f(0f, -5f, 0f));
    top_cam.lookAtDirection(new Vector3f(0,-1,0), Vector3f.UNIT_Y);
    
    Camera front_cam = new Camera(512,512);
    top_cam.setFrustumPerspective(45f, 1f, 1f, 1000f);
    top_cam.setLocation(new Vector3f(0f, 0f, -5f));
    top_cam.lookAtDirection(new Vector3f(0,0,-1), Vector3f.UNIT_Y);
    
    Camera back_cam = new Camera(512,512);
    top_cam.setFrustumPerspective(45f, 1f, 1f, 1000f);
    top_cam.setLocation(new Vector3f(0f, 0f, 5f));
    top_cam.lookAtDirection(new Vector3f(0,0, 1), Vector3f.UNIT_Y);
    
    Camera left_cam = new Camera(512,512);
    top_cam.setFrustumPerspective(45f, 1f, 1f, 1000f);
    top_cam.setLocation(new Vector3f(-5f, 0f, 0f));
    top_cam.lookAtDirection(new Vector3f(-1,0,0), Vector3f.UNIT_Y);
    
    Camera right_cam = new Camera(512,512);
    top_cam.setFrustumPerspective(45f, 1f, 1f, 1000f);
    top_cam.setLocation(new Vector3f(5f, 0f, 0f));
    top_cam.lookAtDirection(new Vector3f(1,0,0), Vector3f.UNIT_Y);
    
    ViewPort top_view = renderManager.createPreView("Top View", top_cam);
    top_view.setClearFlags(true, true, true);
    top_view.setBackgroundColor(ColorRGBA.Blue);
    ViewPort bottom_view = renderManager.createPreView("Bottom View", bottom_cam);
    bottom_view.setClearFlags(true, true, true);
    bottom_view.setBackgroundColor(ColorRGBA.Red);
    
    ViewPort front_view = renderManager.createPreView("Front View", front_cam);
    front_view.setClearFlags(true, true, true);
    front_view.setBackgroundColor(ColorRGBA.Green);
    ViewPort back_view = renderManager.createPreView("Back View", back_cam);
    back_view.setClearFlags(true, true, true);
    back_view.setBackgroundColor(ColorRGBA.Pink);
    
    ViewPort left_view = renderManager.createPreView("Left View", left_cam);
    left_view.setClearFlags(true, true, true);
    left_view.setBackgroundColor(ColorRGBA.Yellow);
    ViewPort right_view = renderManager.createPreView("Right View", right_cam);
    right_view.setClearFlags(true, true, true);
    right_view.setBackgroundColor(ColorRGBA.Gray);
    
    TextureCubeMap cube_Tex = new TextureCubeMap(512, 512, Format.RGBA8);
    cube_Tex.setMinFilter(Texture.MinFilter.Trilinear);
    cube_Tex.setMagFilter(Texture.MagFilter.Bilinear);
    
    FrameBuffer top_Buffer = new FrameBuffer(512, 512, 1);
    top_Buffer.setDepthBuffer(Format.Depth);
    top_view.setOutputFrameBuffer(top_Buffer);        
    FrameBuffer bottom_Buffer = new FrameBuffer(512, 512, 1);
    bottom_Buffer.setDepthBuffer(Format.Depth);
    bottom_view.setOutputFrameBuffer(bottom_Buffer);
    FrameBuffer front_Buffer = new FrameBuffer(512, 512, 1);
    front_Buffer.setDepthBuffer(Format.Depth);
    front_view.setOutputFrameBuffer(front_Buffer);
    FrameBuffer back_Buffer = new FrameBuffer(512, 512, 1);
    back_Buffer.setDepthBuffer(Format.Depth);
    back_view.setOutputFrameBuffer(back_Buffer);
    FrameBuffer left_Buffer = new FrameBuffer(512, 512, 1);

[/java] left_Buffer.setDepthBuffer(Format.Depth);
left_view.setOutputFrameBuffer(left_Buffer);
FrameBuffer right_Buffer = new FrameBuffer(512, 512, 1);
right_Buffer.setDepthBuffer(Format.Depth);
right_view.setOutputFrameBuffer(right_Buffer);

    top_Buffer.addColorTexture(cube_Tex, TextureCubeMap.Face.NegativeX);
    bottom_Buffer.addColorTexture(cube_Tex, TextureCubeMap.Face.PositiveX);
    front_Buffer.addColorTexture(cube_Tex, TextureCubeMap.Face.NegativeY);
    back_Buffer.addColorTexture(cube_Tex, TextureCubeMap.Face.PositiveY);
    left_Buffer.addColorTexture(cube_Tex, TextureCubeMap.Face.NegativeZ);
    right_Buffer.addColorTexture(cube_Tex, TextureCubeMap.Face.PositiveZ);
    
    top_view.attachScene(rootNode);
    bottom_view.attachScene(rootNode);
    front_view.attachScene(rootNode);
    back_view.attachScene(rootNode);
    left_view.attachScene(rootNode);
    right_view.attachScene(rootNode);
    
    mirror_mat.setTexture("Texture", cube_Tex);
}
protected void initGeometry()
{
    Box box2 = new Box(Vector3f.ZERO, 
            1,1,1);
    Geometry cube = new Geometry("Box",box2);
    Material mat_stl = new Material(assetManager,"Common/MatDefs/Misc/Unshaded.j3md");
    Texture tex_ml = assetManager.loadTexture("Interface/Logo/Monkey.jpg");
    mat_stl.setTexture("ColorMap", tex_ml);
    cube.setMaterial(mat_stl);
    cube.move(1, 7, 1);
    rootNode.attachChild(cube);
    
    Box box1 = new Box(Vector3f.ZERO, 
            1,1,1);
    Geometry blue = new Geometry("Box",box1);
    blue.setMaterial(mirror_mat);
    blue.move(0,0,0);
    blue.scale(5);
    rootNode.attachChild(blue);
}

}

I found the problem: when I set the camera, I set the top camera only.