SSRS表达式-从周值中查找一周的第一天

我有一个SSRS报告，该报告将按周细分的VDI池返回唯一的登录计数。例如，对于一月份，它将显示为：

     Week                # of Logins  
2015_JANUARY_WEEK_NO_1       3  
2015_JANUARY_WEEK_NO_2       49

我使用“星期”列链接到另一个报告，该报告将显示所选星期的登录信息，因此我必须获取所选星期的第一天和所选星期的最后一天，并将它们作为参数传递给其他报告。

我知道如何从“周”列中获取年份和周号。

=Mid(Fields!Week.Value,1,4) 

给我一年 =Trim(Mid(Fields!Week.Value,Len(Fields!Week.Value),Len(Fields!Week.Value)))

给我一周。

我发现此T-SQL有效：

DECLARE @WeekNum INT
          , @YearNum char(4);

SELECT @WeekNum = 2 
     , @YearNum = 2015  
-- once you have the @WeekNum and @YearNum set, the following calculates the date range. 

SELECT DATEADD(wk, DATEDIFF(wk, 6, '1/1/' + @YearNum) + (@WeekNum-1), 6) AS StartOfWeek;   
SELECT DATEADD(wk, DATEDIFF(wk, 5, '1/1/' + @YearNum) + (@WeekNum-1), 5) AS EndOfWeek; 

但我不知道如何将其转换为不会引发错误的表达式。

到目前为止，这是我得到的：

=DateAdd("w", DateDiff("w", 6, '1/1/' + (Mid(Fields!Week.Value,1,4))) + (Trim(Mid(Fields!Week.Value,Len(Fields!Week.Value),Len(Fields!Week.Value)))
- 1), 6)

当我尝试在设计视图中运行报表时，它返回一个表达式预期错误。

编辑对不起，我想我应该发布填入报告的原始查询。在下面：

SELECT Convert(varchar(20),UPPER(DATENAME(YEAR, Time)))
    +'_'+CONVERT(varchar(20),UPPER(DATENAME(MONTH, Time)))
    +'_WEEK_NO_'+CONVERT(varchar(10),(DAY(Time) 
    + (DATEPART(DW, DATEADD (MONTH, DATEDIFF (MONTH, 0, Time), 0))-1) -1)/7 + 1) as 'Week'
    , Count(DISTINCT SUBSTRING(ModuleAndEventText,LEN('User ') + 2
    , CHARINDEX(' requested', ModuleAndEventText) - LEN('User ') - 2)) as WeekCount
  FROM VE1_UserLogins
WHERE DesktopId = @Pool
AND ([Time] BETWEEN (@StartDate) and (DATEADD(ms, -1, @EndDate +1)))
GROUP BY Convert(varchar(20),UPPER(DATENAME(YEAR, Time)))
    +'_'+CONVERT(varchar(20),UPPER(DATENAME(MONTH, Time)))
    +'_WEEK_NO_'+CONVERT(varchar(10),(DAY(Time) 
    + (DATEPART(DW, DATEADD (MONTH, DATEDIFF (MONTH, 0, Time), 0))-1) -1)/7 + 1),YEAR(Time),MONTH(Time)
ORDER BY YEAR(Time), MONTH(Time), Week