Android : Android Database returns null

public class DBHelper extends SQLiteOpenHelper {

    SQLiteDatabase dbEvents;


    public DBHelper(Context context) {
        super(context, DB_NAME, null, DB_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE IF NOT EXISTS sampleTable(sampleID INTEGER PRIMARY KEY AUTOINCREMENT,sampleTitle TEXT,sampleDATE BIGINT,trash INTEGER DEFAULT 0) ");
        this.dbEvents=db;

    }

public Integer deleteItem(Integer itemId){
        Log.d("CURSOR:","IM HERE"+eventId);
        if(dbEvents == null){
            Log.d("CURSOR:","IM NOT INTIALIZING");
        }

        return null;
    }

Where I'm getting IM NOT INTIALIZING

I cannot perform DB operation where it throws to Null Pointer Exception.

thanks in advance