Overallocation SQL Query (PS2010)

Hi. I have a query which returns resource and allocated work from PS2010. I appear to have an issue where MSP_EpmAssignment_UserView.AssignmentIsOverallocatedis returning TRUE for a Resource in a particular month and project when in fact he is NOT Over Allocated in PS.

My mind is a little frazzled after a day of looking at the (trimmed down) query below - Please would someone look at the basic JOIN logic and highlight if and where I am going wrong?

SELECT MSP_EpmResource_UserView.ResourceName
		,MSP_EpmAssignmentByDay_UserView.TimeByDay AS TimeByDay
		,MSP_EpmAssignmentByDay_UserView.AssignmentCombinedWork AS AssignmentCombinedWork
		,MSP_EpmAssignmentByDay_UserView.AssignmentWork AS FORECASTWORK
		,MSP_EpmAssignment_UserView.AssignmentStartDate
		,MSP_EpmAssignment_UserView.AssignmentFinishDate
		,MSP_EpmProject_UserView.ProjectName
		,DATENAME(YEAR, MSP_EpmAssignmentByDay_UserView.TimeByDay) AS AssignmentYear
		,MSP_EpmResource_UserView.[Primary Role]
		,DATEADD(wk, DATEDIFF(wk, 0, MSP_EpmAssignmentByDay_UserView.TimeByDay), 0) AS WeekStartDate
		,MSP_EpmResource_UserView.ResourceUID
		,MSP_EpmProject_UserView.ProjectWorkspaceInternalHRef
		,MSP_EpmProject_UserView.[Project Status]
		,MSP_EpmAssignment_UserView.AssignmentIsOverallocated
	FROM MSP_EpmResource_UserView
	INNER JOIN MSP_EpmAssignment_UserView
	INNER JOIN MSP_EpmAssignmentByDay_UserView ON MSP_EpmAssignment_UserView.AssignmentUID = MSP_EpmAssignmentByDay_UserView.AssignmentUID
		AND MSP_EpmAssignment_UserView.ProjectUID = MSP_EpmAssignmentByDay_UserView.ProjectUID ON MSP_EpmResource_UserView.ResourceUID = MSP_EpmAssignment_UserView.ResourceUID 
		INNER JOIN MSP_EpmProject_UserView ON MSP_EpmAssignment_UserView.ProjectUID = MSP_EpmProject_UserView.ProjectUID
		WHERE (
			MSP_EpmAssignmentByDay_UserView.TimeByDay BETWEEN CONVERT(DATETIME, '01-may-2014')
				AND CONVERT(DATETIME, '31-may-2014')
			)
		AND (MSP_EpmAssignmentByDay_UserView.AssignmentWork > 0)
		and MSP_EpmResource_UserView.ResourceName = 'Bob'