Button doesn't work.

public static final String TAG = StoryActivity.class.getSimpleName();


private Story mStory = new Story();

private ImageView mImageView;
private TextView mTextView;
private Page mCurrentPage;
private String mName;
private Button mPreviousButton;
private Button mNextButton;
private ScrollView mScrollView;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_story2);


  //Intent intent = getIntent();
   //mName = intent.getStringExtra(getString(R.string.key_name));

    if(mName == null){
        mName = "Friend";
    }

    Log.d(TAG, mName);

    mImageView = (ImageView)findViewById(R.id.storyImageView);
    mTextView = (TextView)findViewById(R.id.storyTextView);
   mPreviousButton = (Button)findViewById(R.id.previousButton);
   mNextButton = (Button)findViewById(R.id.nextButton);

    mTextView.setMovementMethod(new ScrollingMovementMethod());


    loadPage(0);
}
private void loadPage(int choice){
 mCurrentPage = mStory.getPage(choice);

    Drawable drawable  = getResources().getDrawable(mCurrentPage.getImageId());
    mImageView.setImageDrawable(drawable);

    String pageText = mCurrentPage.getText();
    //add the name if placeholder included.
   //pageText  = String.format(pageText,mName);
    mTextView.setText(pageText);

    if(mCurrentPage.isSingle()){
        mPreviousButton.setVisibility(View.VISIBLE);
        mNextButton.setText("Start From The Begining");
        mNextButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                loadPage(1);
            }
        });

    }else{

        mPreviousButton.setText(mCurrentPage.getChoices().getText1());
        mNextButton.setText(mCurrentPage.getChoices().getText2());

        mPreviousButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                int previousPage = mCurrentPage.getChoices().getPreviousPage();
                loadPage(previousPage);
            }
        });

        mNextButton.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v) {
            int nextPage = mCurrentPage.getChoices().getNextPage();
            loadPage(nextPage);
        }
    });
}}

private int mPreviousPage;
private int mNextPage;



public Choices(int currentPage, String text1, String text2) {
    mPreviousPage = currentPage - 1;
    mText1 = text1;
    mNextPage = currentPage + 1;
    mText2 = text2;

}

public String getText1() {

    return mText1;
}

public void setText1(String text1) {

    mText1 = text1;
}

public String getText2(){
    return mText2;
}

public void setText2(String text2){
  mText2 = text2;
}

public int getPreviousPage() {
  return mPreviousPage;
}

public void setPreviousPage(int previousPage){
  mPreviousPage = previousPage;
}

public int getNextPage() {

    return mNextPage;
}

public void setNextPage(int nextPage) {
    mNextPage = nextPage;
}

private int mPageId;
private int mImageId;
private String mText;
private Choices mChoices;
private boolean mIsSingle = false;

public Page(int pageId, int imageId, String text, Choices choices) {

    mPageId = pageId;
    mImageId = imageId;
    mText = text;
    mChoices = choices;
}

public Page(int pageId, int imageId, String text) {

    mPageId = pageId;
    mImageId = imageId;
    mText = text;
    mChoices = null;
    mIsSingle = true;
}
public int getPageId(){
    return mPageId;
}

public void setPageId(int pageId){
    mPageId = pageId;
}

public int getImageId() {
    return mImageId;
}

public void setImageId(int imageId) {
    mImageId = imageId;
}

public String getText() {
    return mText;
}

public void setText(String text){
    mText = text;
}

public Choices getChoices(){
    return mChoices;
}

public void setChoices(Choices choices){
    mChoices = choices;
}

    public boolean isSingle() {

        return mIsSingle;
    }

    public void setSingle(boolean isFinal) {

        mIsSingle = isFinal;
    }
  }