Sqlite-net get record

I'm using SQLite-net in my UWP app, Now I wanna get some records in GetLocationsWhereIdIs and GetLocations methods but I face an Exception.

    SQLiteAsyncConnection db = new SQLiteAsyncConnection("locDB.db");
    public async Task<List<STLoc>> GetLocationsWhereIdIs(int _id) {
        return await db.Table<STLoc>().Where(c => c.Id == _id).ToListAsync();
    }
    public async Task<List<STLoc>> GetLocations() {
        return await db.QueryAsync<STLoc>("select * from Location ");
    }