How to solve a failure to insert something into SQLite db due to non-existing table?

I'm trying to insert a note into my Android SQLite database, but I get the following error message:

02-04 01:28:19.775 9521-9521/? E/SQLiteDatabase﹕ Error inserting text=Note 0 android.database.sqlite.SQLiteException: no such table: notes (code 1): , while compiling: INSERT INTO notes(text) VALUES (?)

This is my database adapter:

import android.content.ContentValues;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;
import android.util.Log;

/**
 * Created by Friso on 15/2/1.
 */
public class DBAdapter {
    private final static String DATABASE_NAME = "db_aio_organiser";
    private final static int DATABASE_VERSION = 1;

    private final static String TABLE_NOTES = "notes";
    private final static String KEY_NOTES_ID = "id";
    private final static String KEY_NOTES_TEXT = "text";

    private final static String CREATE_TABLE_NOTES = "create table " + TABLE_NOTES +
            " (" + KEY_NOTES_ID + "integer primary key autoincrement, "
            + KEY_NOTES_TEXT + "text not null);";

    private final Context context;

    DatabaseHelper helper;
    SQLiteDatabase db;

    public DBAdapter(Context context) {
        this.context = context;
        helper = new DatabaseHelper(context);
    }

    public DBAdapter open() throws SQLException{
        db = helper.getWritableDatabase();
        return this;
    }

    public void close() {
        db.close();
    }

    public long insertNote(String text) {
        ContentValues values = new ContentValues();
        values.put(KEY_NOTES_TEXT, text);
        return db.insert(TABLE_NOTES, null, values);
    }

    public boolean deleteNote(long id) {
        return db.delete(TABLE_NOTES, KEY_NOTES_ID + "=" + id, null) > 0;
    }

    public Cursor getAllNotes() {
        return db.query(TABLE_NOTES, new String[] {KEY_NOTES_ID, KEY_NOTES_TEXT}, null, null, null, null, null);
    }

    public Cursor getNote(long id) {
        Cursor mCursor = db.query(true, TABLE_NOTES, new String[] {KEY_NOTES_ID, KEY_NOTES_TEXT},
                KEY_NOTES_ID + "=" + id, null, null, null, null, null);
        if (mCursor != null) {
            mCursor.moveToFirst();
        }
        return mCursor;
    }

    public boolean updateNote(long id, String text) {
        ContentValues values = new ContentValues();
        values.put(KEY_NOTES_TEXT, text);
        return db.update(TABLE_NOTES, values, KEY_NOTES_ID + "=" + id, null) > 0;
    }

    private static class DatabaseHelper extends SQLiteOpenHelper {
        private DatabaseHelper(Context context) {
            super(context, DATABASE_NAME, null, DATABASE_VERSION);
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            try {
                db.execSQL(CREATE_TABLE_NOTES);
            } catch (SQLException e) {
                Log.e("DBAdapter", "failed to create table notes");
            }
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

        }
    }
}

What did I do wrong?