SQL 按年龄范围分组

SQL 2005， 我有一个包含“ages_c”列的表，我需要按年龄范围对记录进行分组。 这是我在这个网站上找到的查询，它让我达到了 90%，但“分组依据”出错，*无效的列名“age_range”*

 select 
  case
   when age_c <18 then 'Under 18'
   when age_c between 18 and 24 then '18-24'
   when age_c between 25 and 34then '25-34'
 END as age_range, 
 Count(*) as count
 from contacts
 group by age_range
 order by age_range

当我按“age_c”分组和排序时，我的结果是：

  Under 18  1
  18-24 1
  18-24 1
  25-34 1

我想要的是：

 Under 18   1
  18-24 2      
  25-34 1

Thanks.

尝试用这种方法代替：

 SELECT SUM(CASE WHEN age_c < 18 THEN 1 ELSE 0 END) AS [Under 18],
        SUM(CASE WHEN age_c BETWEEN 18 AND 24 THEN 1 ELSE 0 END) AS [18-24],
        SUM(CASE WHEN age_c BETWEEN 25 AND 34 THEN 1 ELSE 0 END) AS [25-34]
 FROM contacts