SUM named union sub queries

Hi -- I have inherited a sql statement comprising of two subqueries (WeeklyAssignment and MasterWeeklyAssignment) and a UNION join. Against our database the below query returns two rows (values 0.5 and 0.75) as the particular resource is working on two projects. How do I total these so that I only ever get one row returned, which in this case should be 1.25 (0.5 + 0.75)? I have tried changing the group by to no avail - I'm not sure how to total when there are named sub queries. Thanks!

SELECT SUM(WORKDEMANDFTE)
FROM (
	SELECT 
	     dbo.MSP_EpmResource_UserView.ResourceName
		,ISNULL(dbo.MSP_EpmAssignmentByDay_UserView.AssignmentWork, 0) / 8 / dbo.DATAMART_WSSLIST_RESOURCE_CAPACITY_FTE.[wss_Working days in month_Double] AS [WORKDEMANDFTE]
		,dbo.MSP_EpmProject_UserView.ProjectName
		,DATENAME(MONTH, MSP_EpmAssignmentByDay_UserView.TimeByDay) AS AssignmentMonth
		,DATENAME(YEAR, MSP_EpmAssignmentByDay_UserView.TimeByDay) AS AssignmentYear
		,dbo.MSP_TimeByDay_OlapView.CalendarMemberNameYear
		,dbo.MSP_EpmResource_UserView.ResourceUID
	FROM dbo.MSP_EpmResource_UserView
	INNER JOIN dbo.MSP_EpmAssignment_UserView
	INNER JOIN dbo.MSP_EpmAssignmentByDay_UserView ON dbo.MSP_EpmAssignment_UserView.AssignmentUID = dbo.MSP_EpmAssignmentByDay_UserView.AssignmentUID
		AND dbo.MSP_EpmAssignment_UserView.ProjectUID = dbo.MSP_EpmAssignmentByDay_UserView.ProjectUID ON dbo.MSP_EpmResource_UserView.ResourceUID = dbo.MSP_EpmAssignment_UserView.ResourceUID INNER JOIN dbo.MSP_EpmProject_UserView ON dbo.MSP_EpmAssignment_UserView.ProjectUID = dbo.MSP_EpmProject_UserView.ProjectUID
		AND dbo.MSP_EpmAssignmentByDay_UserView.ProjectUID = dbo.MSP_EpmProject_UserView.ProjectUID INNER JOIN dbo.MSP_TimeByDay_OlapView ON dbo.MSP_EpmAssignmentByDay_UserView.TimeByDay = dbo.MSP_TimeByDay_OlapView.TimeByDay INNER JOIN dbo.MSP_EpmTask ON dbo.MSP_EpmAssignment_UserView.TaskUID = dbo.MSP_EpmTask.TaskUID INNER JOIN dbo.DATAMART_WSSLIST_RESOURCE_CAPACITY_FTE ON dbo.MSP_EpmResource_UserView.[Primary Role] = DATAMART_WSSLIST_RESOURCE_CAPACITY_FTE.[wss_Primary Role_String]
		AND DATENAME(MONTH, MSP_EpmAssignmentByDay_UserView.TimeByDay) = DATAMART_WSSLIST_RESOURCE_CAPACITY_FTE.[wss_Month_String]
		AND DATENAME(YEAR, MSP_EpmAssignmentByDay_UserView.TimeByDay) = DATAMART_WSSLIST_RESOURCE_CAPACITY_FTE.[wss_Year_String] 
		AND (dbo.MSP_EpmProject_UserView.[Project Status] = 'Open')
		AND (dbo.MSP_EpmResource_UserView.ResourceUID = '8CB5EADB-B2C0-4BAF-A938-40AC81F9C4FB')
		AND (DATENAME(YEAR, MSP_EpmAssignmentByDay_UserView.TimeByDay)) = '2014'
		AND (DATENAME(MONTH, MSP_EpmAssignmentByDay_UserView.TimeByDay)) = 'February'
		AND (dbo.MSP_EpmAssignmentByDay_UserView.AssignmentWork > 0)
		) AS WeeklyAssignment
INNER JOIN (
	SELECT dbo.MSP_EpmProject.ProjectName AS MProject
		,dbo.MSP_EpmTask.TaskName AS ChildProject
	FROM dbo.MSP_EpmProject
	INNER JOIN dbo.MSP_EpmTask ON dbo.MSP_EpmProject.ProjectUID = dbo.MSP_EpmTask.ProjectUID
	WHERE (dbo.MSP_EpmTask.TaskIsProjectSummary = 0)
	) AS MasterProjectDetails 
	ON WeeklyAssignment.ProjectName = MasterProjectDetails.ChildProject
UNION


SELECT SUM(WORKDEMANDFTE)
FROM (
	SELECT 
		 dbo.MSP_EpmResource_UserView.ResourceName
		,dbo.MSP_EpmAssignmentByDay_UserView.TimeByDay AS TimeByDay
		,dbo.MSP_EpmAssignmentByDay_UserView.AssignmentWork AS FORECASTWORK
		,ISNULL(dbo.MSP_EpmAssignmentByDay_UserView.AssignmentWork, 0) / 8 / dbo.DATAMART_WSSLIST_RESOURCE_CAPACITY_FTE.[wss_Working days in month_Double] AS [WORKDEMANDFTE]
		,dbo.MSP_EpmProject_UserView.ProjectName
		,DATENAME(MONTH, MSP_EpmAssignmentByDay_UserView.TimeByDay) AS AssignmentMonth
		,DATENAME(YEAR, MSP_EpmAssignmentByDay_UserView.TimeByDay) AS AssignmentYear
		,dbo.MSP_TimeByDay_OlapView.CalendarMemberNameYear
		,dbo.MSP_EpmResource_UserView.ResourceUID
	FROM dbo.MSP_EpmResource_UserView
	INNER JOIN dbo.MSP_EpmAssignment_UserView
	INNER JOIN dbo.MSP_EpmAssignmentByDay_UserView ON dbo.MSP_EpmAssignment_UserView.AssignmentUID = dbo.MSP_EpmAssignmentByDay_UserView.AssignmentUID
		AND dbo.MSP_EpmAssignment_UserView.ProjectUID = dbo.MSP_EpmAssignmentByDay_UserView.ProjectUID ON dbo.MSP_EpmResource_UserView.ResourceUID = dbo.MSP_EpmAssignment_UserView.ResourceUID INNER JOIN dbo.MSP_EpmProject_UserView ON dbo.MSP_EpmAssignment_UserView.ProjectUID = dbo.MSP_EpmProject_UserView.ProjectUID
		AND dbo.MSP_EpmAssignmentByDay_UserView.ProjectUID = dbo.MSP_EpmProject_UserView.ProjectUID INNER JOIN dbo.MSP_TimeByDay_OlapView ON dbo.MSP_EpmAssignmentByDay_UserView.TimeByDay = dbo.MSP_TimeByDay_OlapView.TimeByDay INNER JOIN dbo.MSP_EpmTask ON dbo.MSP_EpmAssignment_UserView.TaskUID = dbo.MSP_EpmTask.TaskUID INNER JOIN dbo.DATAMART_WSSLIST_RESOURCE_CAPACITY_FTE ON dbo.MSP_EpmResource_UserView.[Primary Role] = DATAMART_WSSLIST_RESOURCE_CAPACITY_FTE.[wss_Primary Role_String]
		AND DATENAME(MONTH, MSP_EpmAssignmentByDay_UserView.TimeByDay) = DATAMART_WSSLIST_RESOURCE_CAPACITY_FTE.[wss_Month_String]
		AND DATENAME(YEAR, MSP_EpmAssignmentByDay_UserView.TimeByDay) = DATAMART_WSSLIST_RESOURCE_CAPACITY_FTE.[wss_Year_String] 
		AND (dbo.MSP_EpmProject_UserView.[Project Status] = 'Open')
	AND (dbo.MSP_EpmResource_UserView.ResourceUID = '8CB5EADB-B2C0-4BAF-A938-40AC81F9C4FB')
		AND (DATENAME(YEAR, MSP_EpmAssignmentByDay_UserView.TimeByDay)) = '2014'
		AND (DATENAME(MONTH, MSP_EpmAssignmentByDay_UserView.TimeByDay)) = 'February'
		AND (dbo.MSP_EpmAssignmentByDay_UserView.AssignmentWork > 0)
	) AS MasterWeeklyAssignment

GROUP BY ProjectName