Unable to Download the file and got closed BoxException.

I am using below code to download the file but i got the BoxException as closed.Can you tell the process how to download the box file.

try {



                    File file;
                    file=createFile();

                    BoxDownload fileDownload = mFileApi.getDownloadRequest(file, boxItem.getId())

                            .setProgressListener(new ProgressListener() {
                                @Override
                                public void onProgressChanged(long numBytes, long totalBytes) {

                                    // Update a progress bar, etc.
                                }
                            })
                            .send();

                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {


                            Log.e("fileDonload","is: "+fileDownload);


                        }
                    });


                } catch (BoxException | IOException e) {

                    Log.e("DownloadException:","is :"+e.getMessage());
                    e.printStackTrace();
                }