Android app crashes when write Database

I want to write some data into SQLite database. In my application I have a main singleton class with code:

public class Singleton extends Application {

    public static DBHelper dbHelper;
    public static SQLiteDatabase db;

    @Override
    public void onCreate() {
        super.onCreate();
        dbHelper = new DBHelper(this);
        db = dbHelper.getWritableDatabase();

    }
}

DBHelper.java:

public class DBHelper extends SQLiteOpenHelper {

    public DBHelper(Context context) {
        super(context, "myDB", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE AlarmListTable ("
            + "id integer primary key autoincrement,"
            + "time text,"
            + "date text,"
            + "comment text,"
            + ");");

    }

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

    }
}

I have an activity in which I have a method:

ContentValues cv = new ContentValues();
cv.put("time", entTime.getText().toString());
cv.put("date", entTime.getText().toString());
cv.put("comment", entTime.getText().toString());
Singleton.db.insert("AlarmListTable", null, cv);

But application crashes. Help me please. What is wrong with it?