AVG日期差异SSRS - Oracle数据源CASE声明

Question

我有一个在Oracle中运行良好的查询。当在SSRS中的报告中使用查询时，我得到....指定的强制转换是无效的。来自下面查询的字符串以及已经尝试过的示例

原始查询

AVG(
  CASE 
    WHEN IDSTATUS = '1' 
      THEN (COLLECTED_DATE - START_DATE) 
    ELSE NULL 
  END
) AS "AVG COLLECTED TIME"

尝试修复

AVG(
  CASE 
    WHEN IDSTATUS = '1' 
      THEN TO_NUMBER((COLLECTED_DATE - START_DATE)) 
    ELSE NULL 
  END
) AS "AVG COLLECTED TIME"

也试过

CAST(     
AVG(  
  CASE   
    WHEN IDSTATUS = '1'   
      THEN TO_NUMBER((COLLECTED_DATE - START_DATE))   
    ELSE NULL   
  END  
) AS NUMBER) AS "AVG COLLECTED TIME"  

AND

AVG(CAST(  
  CASE   
    WHEN IDSTATUS = '1'   
      THEN TO_NUMBER((COLLECTED_DATE - START_DATE))   
    ELSE NULL   
  END AS NUMBER)  
) AS "AVG COLLECTED TIME"