How to make Scroll method works in the App?

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);
    mScrollView = (ScrollView)findViewById(R.id.SCROLLER_ID);

    loadPage(0);
}
private void loadPage(int choice){
 mCurrentPage = mStory.getPage(choice);
    //edw prepei na kanw kati gia to previous
    //mPreviousPage = 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.INVISIBLE);
        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);
        }
    });
}}

<ImageView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:id="@+id/storyImageView"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:src="@drawable/page0"
    android:scaleType="fitXY"
    android:adjustViewBounds="true" />

<ScrollView
    android:id="@+id/SCROLLER_ID"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:scrollbars="vertical"
    android:fillViewport="true"/>

<TextView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text=""
    android:id="@+id/storyTextView"
    android:layout_below="@+id/storyImageView"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:paddingLeft="30dp"
    android:paddingRight="30dp"
    android:paddingTop="15dp"
    android:lineSpacingMultiplier="1.2"
    />

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Back"
    android:id="@+id/previousButton"
    android:layout_marginBottom="45dp"
    android:background="@android:color/white"
    android:textColor="#3a8aec"
    android:layout_alignParentBottom="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignParentRight="true"
    android:layout_alignWithParentIfMissing="false"
    android:layout_alignParentTop="false"/>

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Next"
    android:id="@+id/nextButton"
    android:background="@android:color/white"
    android:textColor="#ff3a8aec"
    android:layout_alignTop="@+id/previousButton"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true"
    android:layout_alignParentBottom="false"
    android:layout_alignWithParentIfMissing="false"
    android:layout_alignParentTop="false"/>