The scoreboard doesn't stick to the anchor point

[yashmanuda]

Whenever I move my phone the scoreboard moves as well, it doesn't stick to the anchor point. I think, the position of the scoreboard is not getting updated to the position of the anchor point. May I know why is this happening?
Here is my Update() function

void Update()
    {
        // The session status must be Tracking in order to access the Frame.
        if (Session.Status != SessionStatus.Tracking)
        {
            return;
        }

        // If there is no plane, then return
        if (detectedPlane == null)
        {
            return;
        }

        // Check for the plane being subsumed.
        // If the plane has been subsumed switch attachment to the subsuming plane.
        while (detectedPlane.SubsumedBy != null)
        {
            detectedPlane = detectedPlane.SubsumedBy;
        }

        // Make the scoreboard face the viewer
        transform.LookAt(firstPersonCamera.transform);

        // Move the position to stay consistent with the plane
        transform.position = new Vector3(transform.position.x,
            detectedPlane.CenterPose.position.y + yOffset,
            transform.position.z);
    }

I am also including my CreateAnchor() function

private void CreateAnchor()
    {
        // Create the position of the anchor by raycasting a point towards the top of the screen.
        Vector2 pos = new Vector2(Screen.width * .5f, Screen.height * .90f);
        Ray ray = firstPersonCamera.ScreenPointToRay(pos);
        Vector3 anchorPosition = ray.GetPoint(5f);

        // Create the anchor at that point.
        if (anchor != null)
        {
            DestroyObject(anchor);
        }
        anchor = detectedPlane.CreateAnchor(new Pose(anchorPosition, Quaternion.identity));

        // Attach the scoreboard to the anchor.
        transform.position = anchorPosition;
        transform.SetParent(anchor.transform);

        // Record the y offset from the plane.
        yOffset = transform.position.y - detectedPlane.CenterPose.position.y;

        // Finally, enable the renderers.
        foreach (Renderer r in GetComponentsInChildren<Renderer>())
        {
            r.enabled = true;
        }
    }

[Deleted user]

Same. I got this error from logcat

05-19 15:29:20.409 2841 2860 E Unity : NullReferenceException: Object reference not set to an instance of an object
05-19 15:29:20.409 2841 2860 E Unity : at SceneController.SetSelectedPlane (GoogleARCore.DetectedPlane selectedPlane) [0x00023] in B:\Unity\Test\Test2\Assets\SceneController.cs:34
05-19 15:29:20.409 2841 2860 E Unity : at SceneController.ProcessTouches () [0x00064] in B:\Unity\Test\Test2\Assets\SceneController.cs:27
05-19 15:29:20.409 2841 2860 E Unity : at SceneController.Update () [0x00023] in B:\Unity\Test\Test2\Assets\SceneController.cs:69