query ddatetime

HI ,

In my below query it is not  calculating hours correctly

WITH CTE_Sum AS (SELECT        e.EmployeeName, d.ProjectName, DATEADD(ms, SUM(DATEDIFF(ms, '00:00:00.000', d.Total)), '00:00:00.000') AS TotTime
                                            FROM            DetailsTable AS d INNER JOIN
                                                                     EmployeeTSDates AS e ON d.ServiceID = e.TSID
                                            WHERE         (e.EmployeeName = 'Howard Hall') AND (e.TSStartDate >= '5/3/2015')AND (e.TSEndDate <='5/9/2015')
                                            GROUP BY e.EmployeeName, d.ProjectName)
    SELECT        ProjectName,    'Howard Hall', '5/3/2015',
                             '5/9/2015', CAST(DATEDIFF(DAY, 0, TotTime) * 24 + DATEPART(HOUR, TotTime) AS varchar(4)) + ':' + RIGHT('00' + CAST(DATEPART(MINUTE,
                              TotTime) AS varchar(2)), 2) + ':' + RIGHT('00' + CAST(DATEPART(SECOND, TotTime) AS varchar(2)), 2) AS TotalHours
     FROM            CTE_Sum AS CTE_Sum_1

Output for the above query
projecnma             empname       startdatedate    enddate   total
Fisher 605 PA	     Howard Hall	5/3/2015	5/9/2015	0:30:00
Other	             Howard Hall	5/3/2015	5/9/2015	11:00:00
SOCiFi        	     Howard Hall	5/3/2015	5/9/2015	20:45:00
SOCiFi / DFWMSDC	Howard Hall	5/3/2015	5/9/2015	9:15:00

data entered in database

SELECT
      [ProjectName]

      ,[Total]

  FROM Detailstable

output for the query
projectname     total
Other     	 00:15:00
Fisher 605 PA	 00:15:00
Other	         04:15:00
SOCiFi     	03:15:00
Other	         00:15:00
Fisher 605 PA	00:15:00
Other	        03:30:00
SOCiFi 	       04:00:00
SOCiFi / DFWMSDC	05:15:00
Other	         00:30:00
Other	         02:00:00
Other	           00:15:00
SOCiFi    	04:45:00
SOCiFi / DFWMSDC	04:00:00
SOCiFi 	           08:45:00