AsyncTask no funciona correctamente cuando se llama repetidamente desde un hilo

I am making an app which sends update to web server when a songs starts playing...I do the the web server update through asynctask however some times some information gets skipped and some infos are sent repeatedly. In some case asyntask remain in running state making it not executing after that. Main thread works good.

I declared the instance like this in MainActivity

    private static AsyncTask<Void, Void, Void> mTask = null;

code for Asynctask is

private class SendingData extends AsyncTask<Void,Void,Void>{

        @Override
         protected void onPreExecute(){
            //some task              
         }         
        protected void onPostExecute(Void params){
            Log.d("Tesing","After Post");
            super.onPostExecute(params);         
            }
        @Override
        protected Void doInBackground(Void... arg0) {
            sendPost();
            return null;
        }

     }  

My call to asynctask when a new song changes in main thread. This is a repetitive call

 if(mTask.getStatus() == AsyncTask.Status.FINISHED){
                   // My AsyncTask is done and onPostExecute was called
                   Log.d("AsyncTask Status","Finished");
                  mTask = new SendingData();
                  mTask.executeOnExecutor(AsyncTask.SERIAL_EXECUTOR);

              }else if(mTask.getStatus() == AsyncTask.Status.PENDING){
                  Log.d("AsyncTask Status","Pending");
                  try {
                    Thread.sleep(10000);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                  mTask.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
              }