Get Time Difference - Non functioning code

public long totalRouteTime(int routeNo)
    {
        long minTime, maxTime, diffTime = 0;
        SQLiteDatabase db = getReadableDatabase();
        try {
        Cursor results = db.rawQuery("SELECT MAX(" + TIME + ") FROM " + TABLE_NAME + " WHERE " + ROUTE_NUMBER + " == " + routeNo, null);
        if (results.moveToFirst()) {
            maxTime = results.getLong(0);
        }
        results.close();
    } catch (Exception e) {
        Log.e(FixOpenHelper.class.getName(), "Unable to get maxTime for Route "+ routeNo+".", e);
    }
        return diffTime;
    }