Custom ChassisType Report – wrong counts

See the full details within the forum https://social.technet.microsoft.com/Forums/en-US/configmgrreporting/thread/d8477233-4b10-4a6d-a5ea-de73abc9b815/

declare @Manufacturer0 as varchar(250)

set @Manufacturer0 = 'All'

declare @Version0 as varchar(250)

set @Version0 = 'All'

declare @CollectionID as varchar(250)

set @CollectionID = 'SMS00001'



SELECT 

  SE.ChassisTypes0,

  count (*) as ChassisCount 

FROM

  dbo.v_GS_SYSTEM_ENCLOSURE SE

  INNER JOIN dbo.v_GS_OPERATING_SYSTEM OS ON OS.ResourceID = SE.ResourceID

  INNER JOIN dbo.v_FullCollectionMembership FCM ON FCM.ResourceID = SE.ResourceID

WHERE

  (SE.Manufacturer0 = @Manufacturer0 or @Manufacturer0 = 'All')

  AND (OS.Version0 = @Version0 or @Version0 = 'All')

  AND (FCM.CollectionID = @CollectionID or @CollectionID = 'All')

GROUP BY 

  SE.ChassisTypes0