private void startProgressDialog() {

    if (progressDialog == null) {

      progressDialog = WTProgressDialog.createDialog(this);

      progressDialog.setMessage(getResources().getString(R.string.operation_proceeding));
    }

    progressDialog.show();
  }
 private void stopProgressDialog() {
   if (progressDialog != null) {
     progressDialog.dismiss();
     progressDialog = null;
   }
 }