Android: How I can take Bracketing photos using SonyCamera remote API

This issue is troubling me until 1 week. I want to take picture like bracketing but in Sony Camera API its not support. so I coded it like continuously take 5 pictures with different value (0,+2,-2,-4,+4) using loop. (using button for it, and when press the button it should take picture 5 times) U can see the code in below:
This code for set Shutter Speed on camera

This code for taking picture:

private void takePicture() {
    if (mLiveviewSurface == null || !mLiveviewSurface.isStarted()) {
        DisplayHelper.toast(getApplicationContext(), R.string.msg_error_take_picture);
        return;
    }
    new Thread() {
        @Override
        public void run() {
            try {
                JSONObject replyJson = mRemoteApi.actTakePicture();
                JSONArray resultsObj = replyJson.getJSONArray("result");
                JSONArray imageUrlsObj = resultsObj.getJSONArray(0);
                String postImageUrl = null;
                if (1 <= imageUrlsObj.length()) {
                    postImageUrl = imageUrlsObj.getString(0);                        continousShottingWithDifferentShutterValue();

                }
                if (postImageUrl == null) {
                    Log.w(TAG, "takePicture: post image URL is null.");
                    DisplayHelper.toast(getApplicationContext(), //
                            R.string.msg_error_take_picture);
                    return;
                }
                // Show progress indicator
                DisplayHelper.setProgressIndicator(SonyCameraActivity.this, false);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }.start();
}

and this is for loop:

int val, posVal = 0;
int currentShutterSpeed = 0;

private void continousShottingWithDifferentShutterValue() {

    if (val == 0) {
        currentShutterSpeed = -5;
        setShutterSpeed(currentShutterSpeed);
        val++;
    } else if (val == 1) {
        currentShutterSpeed = 5;
        setShutterSpeed(currentShutterSpeed);
        val++;
    } else if (val == 2) {
        currentShutterSpeed = -10;
        setShutterSpeed(currentShutterSpeed);
        val++;
    } else if (val == 3) {
        currentShutterSpeed = 10;
        setShutterSpeed(currentShutterSpeed);
        val++;
    } else if (val == 4) {
        setShutterSpeedVal0(0);
        posVal++;
    }
    if (posVal == 3) {
        posVal = 0;
        val = 0;
    }
}

But when I take picture sometimes shutterSpeed or takePicture is getting error and loop is stop.

Error types are: setShutterSpeed IOExeption error: 500; or setShutterSpeed is not set. Someone works with Sonycamera remote API and has any idea how to fix it or take picture 5 times with different value. will thankful for any idea. Thanks

I solved the problem. it was a shutter speed value error. As u know in Sony Camera Api there is not have the value of shutter speed and I wrote it as in camera settings. and JSON request and response is not match so its shows error 500. If someone wants to use shutter speed value: here it is:

String shutterValue[] = {"30\"", "25\"", "20\"", "15\"", "13\"", "10\"", "8\"", "6\"",
        "5\"", "4\"", "3.2\"", "2.5\"", "2\"", "1.6\"", "1.3\"", "1\"", "0.8\"", "0.6\"", "0.5\"",
        "0.4\"", "1/3", "1/4", "1/5", "1/6", "1/8", "1/10", "1/13", "1/15", "1/20", "1/25", "1/30",
        "1/40", "1/50", "1/60", "1/80", "1/100", "1/125", "1/160", "1/200", "1/250", "1/320", "1/400",
        "1/500", "1/640", "1/800", "1/1000", "1/1250", "1/1600", "1/2000", "1/2500", "1/3200", "1/4000"};