Problème boutons

Je clique dessus mais rien ne se passe.

package com.dfrobot.angelo.blunobasicdemo;

import android.content.Context;
import android.os.Bundle;
import android.content.Intent;
import android.util.Log;
import android.util.LogPrinter;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ScrollView;
import android.widget.TextView;

public class MainActivity  extends BlunoLibrary {
	private Button buttonScan;
	private Button buttonAvance;
	private Button buttonSerialSend;
	private EditText serialSendText;
	private TextView serialReceivedText;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
        onCreateProcess();														//onCreate Process by BlunoLibrary


        serialBegin(115200);													//set the Uart Baudrate on BLE chip to 115200

        //serialReceivedText=(TextView) findViewById(R.id.serialReveicedText);	//initial the EditText of the received data
        //serialSendText=(EditText) findViewById(R.id.serialSendText);			//initial the EditText of the sending data

		buttonAvance = (Button) findViewById(R.id.button_avance);
		buttonAvance.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View view) {
				serialSend("a");
			}
		});

		Button ButtonRecule = (Button) findViewById(R.id.button_recule);
		ButtonRecule.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				serialSend("r");
			}
		});

		Button ButtonDroite = (Button) findViewById(R.id.button_droite);
		ButtonDroite.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				serialSend("d");
			}
		});

		Button ButtonGauche = (Button) findViewById(R.id.button_gauche);
		ButtonGauche.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				serialSend("g");
			}
		});

        buttonScan = (Button) findViewById(R.id.buttonScan);					//initial the button for scanning the BLE device
        buttonScan.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub

				buttonScanOnClickProcess();										//Alert Dialog for selecting the BLE device
			}
		});
	}

	protected void onResume(){
		super.onResume();
		System.out.println("BlUNOActivity onResume");
		onResumeProcess();														//onResume Process by BlunoLibrary
	}
	
	
	
	@Override
	protected void onActivityResult(int requestCode, int resultCode, Intent data) {
		onActivityResultProcess(requestCode, resultCode, data);					//onActivityResult Process by BlunoLibrary
		super.onActivityResult(requestCode, resultCode, data);
	}
	
    @Override
    protected void onPause() {
        super.onPause();
        onPauseProcess();														//onPause Process by BlunoLibrary
    }
	
	protected void onStop() {
		super.onStop();
		onStopProcess();														//onStop Process by BlunoLibrary
	}
    
	@Override
    protected void onDestroy() {
        super.onDestroy();	
        onDestroyProcess();														//onDestroy Process by BlunoLibrary
    }

	@Override
	public void onConectionStateChange(connectionStateEnum theConnectionState) {//Once connection state changes, this function will be called
		switch (theConnectionState) {											//Four connection state
		case isConnected:
			buttonScan.setText("Connected");
			break;
		case isConnecting:
			buttonScan.setText("Connecting");
			break;
		case isToScan:
			buttonScan.setText("Scan");
			break;
		case isScanning:
			buttonScan.setText("Scanning");
			break;
		case isDisconnecting:
			buttonScan.setText("isDisconnecting");
			break;
		default:
			break;
		}
	}

	@Override
	public void onSerialReceived(String theString) {							//Once connection data received, this function will be called
		// TODO Auto-generated method stub
		serialReceivedText.append(theString);							//append the text into the EditText
		//The Serial data from the BLUNO may be sub-packaged, so using a buffer to hold the String is a good choice.
		((ScrollView)serialReceivedText.getParent()).fullScroll(View.FOCUS_DOWN);
	}

}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity"
    android:focusable="true"
    android:focusableInTouchMode="true">

    <ScrollView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/scrollView"
        android:layout_alignParentBottom="true"
        android:layout_below="@+id/buttonScan"
        android:visibility="gone">

        <TextView
            android:id="@+id/serialReveicedText"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:ems="10"
            android:textSize="10sp"
            android:layout_below="@+id/editText2"
            android:layout_alignStart="@+id/editText2"
            android:layout_alignEnd="@+id/serialSendText"
            android:layout_alignParentBottom="true" />
    </ScrollView>

    <Button
        android:id="@+id/buttonSerialSend"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Send Data"
        android:layout_centerHorizontal="true"
        android:visibility="gone" />

    <Button
        android:id="@+id/buttonScan"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Scan"
        android:layout_alignParentTop="true"
        android:layout_alignParentEnd="true" />

    <ImageView
        android:layout_width="147dp"
        android:layout_height="138dp"
        android:id="@+id/flecheRecule"
        android:src="@drawable/fleche_gauche"
        android:layout_centerVertical="true"
        android:layout_alignParentStart="true" />

    <ImageView
        android:layout_width="138dp"
        android:layout_height="147dp"
        android:id="@+id/flecheDroite"
        android:src="@drawable/fleche_bas"
        android:layout_alignParentBottom="true"
        android:layout_alignEnd="@+id/flecheGauche" />

    <ImageView
        android:layout_width="147dp"
        android:layout_height="138dp"
        android:id="@+id/flecheAvance"
        android:src="@drawable/fleche_droite"
        android:layout_centerVertical="true"
        android:layout_alignParentEnd="true" />

    <ImageView
        android:layout_width="138dp"
        android:layout_height="147dp"
        android:id="@+id/flecheGauche"
        android:src="@drawable/fleche_haut"
        android:layout_alignParentTop="true"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="147dp"
        android:visibility="invisible"
        android:id="@+id/button_gauche"
        android:layout_gravity="center_horizontal|top"
        android:layout_alignEnd="@+id/flecheGauche"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="138dp"
        android:visibility="invisible"
        android:id="@+id/button_recule"
        android:layout_gravity="center|bottom"
        android:layout_centerVertical="true"
        android:layout_alignParentStart="true"
        android:layout_alignEnd="@+id/flecheRecule" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="147dp"
        android:visibility="invisible"
        android:id="@+id/button_avance"
        android:layout_gravity="center_horizontal|top"
        android:layout_alignBottom="@+id/flecheAvance"
        android:layout_alignParentEnd="true"
        android:layout_alignTop="@+id/flecheAvance"
        android:layout_alignStart="@+id/flecheAvance" />

    <Button
        android:layout_width="154dp"
        android:visibility="invisible"
        android:layout_height="100dp"
        android:id="@+id/button_droite"
        android:layout_gravity="end|bottom"
        android:layout_alignParentStart="true"
        android:layout_alignBottom="@+id/flecheDroite"
        android:layout_alignEnd="@+id/flecheDroite"
        android:layout_alignTop="@+id/flecheDroite" />

</RelativeLayout>

android:visibility="invisible" 

serialSend("g");

serialSend()

serialSend()