我正在使用VB.NET和MySQL在MVC2中进行开发，尝试将简单的SQL查询转换为LINQ时遇到问题。

SQL查询：

SELECT Location_Number, sum(Column1) as totalC1, sum(Column2) as totalC2
FROM MyTable 
WHERE year = 2010 and month = 8
GROUP BY Location_Number 
ORDER BY Location_Number

LINQ查询：

From r In MyTable _
Where r.Year = 2010 And r.Month = 8 _
Group r By LN = r.Location_Number Into l = Group _
Order By LN _
Select New With { _
  .Location_Number = LN, _
  .DepositCount = l.Sum(Function(r) r.Column1), _
  .OtherCount = l.Sum(Function(r) r.Column2) _
}

生成的错误是：

执行命令定义时发生错误。有关详细信息，请参见内部异常。

内部异常是：

“字段列表”中的未知列“ GroupBy1.K1”

这是LINQ生成的SQL：

SELECT  `Project1`.`Location_Number`,   `Project1`.`C1`,   `Project1`.`C2`  
FROM (
    SELECT  `GroupBy1`.`A1` AS `C1`,   `GroupBy1`.`A2` AS `C2`,   `GroupBy1`.`K1` AS `Location_Number`
    FROM (
            SELECT  Sum(`Column1`) AS `A1`,   Sum(`Column2`) AS `A2`  
            FROM `MyTable` AS `Extent1`  
            WHERE (`Extent1`.`Year` = @p__linq__0) AND (`Extent1`.`Month` = @p__linq__1)   
            GROUP BY   `Extent1`.`Location_Number`
    ) AS `GroupBy1`
) AS `Project1`   
ORDER BY   `Location_Number` ASC

查看该查询，很容易找出导致错误的原因。简而言之，最内部的查询仅返回2列，而其上方的查询试图选择SELECT3，因此出现“未知列错误”。那么为什么会这样呢？我的LINQ查询出了什么问题？

谢谢