Why my method is not working properly?

I have a database that represents shop stock. The problem is, that the method purchase() doesn't work and I don't know why. Basically, I want from it to open the database, get a specific value from index (everything orks until this point) and update that value by adding 1 and updating database. But it doesn't show any errors when executiong, it's simply not working. Here is my code for purchasing the items.

public void purchase(int ID){
    int index = numberOfLives();
    ContentValues cv = new ContentValues();
    cv.put(fItemNumberOfPurchases, index);
    sqLiteDatabase.update(tTableName, cv, fItemID+"=?", new String []{String.valueOf(ID)});
}

here is numberOfLives method:

public int numberOfLives(){
    int ID = 1;
    sqLiteDatabase = this.getWritableDatabase();
    String[] mySearch = new String[]{String.valueOf(ID)};
    Cursor myCursor = sqLiteDatabase.rawQuery("SELECT "+ fItemNumberOfPurchases +" FROM "+ tTableName +" WHERE "+ fItemID +"=?",mySearch);
    myCursor.moveToFirst();
    int index = myCursor.getColumnIndex(fItemNumberOfPurchases);
    index = index +3;
    myCursor.close();
    return index;
}

and this is how I purchase the stuff:

lives.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            myDB.purchase(1);
            int abc = myDB.numberOfLives();
            price1.setText(String.valueOf(abc));
        }
    });

where is the problem ?