SQL Group BY SELECT CASE

Question

I have the query below to select some records and a Boolean "Isbranch" that indicates whether to select the branch or not. The problem is that when it is false the results are not getting grouped.

Ex.

Isbranch = True

29/05/2016 | Route1 | 5 | Branch1

29/05/2016 | Route1 | 5 | Branch2

Isbranch = False

29/05/2016 | Route1 | 5 | B

29/05/2016 | Route1 | 5 | B

I would like to have the following result:

Isbranch = False

29/05/2016 | Route1 | 10 | B

Note. in case I remove the Branch column the grouping works.

SELECT 
    {Order}.[AssignedDate]      AssignedDate,
    {Order}.[RouteCode]         RouteCode,
    COUNT({Order}.[Sequence])   Seq,
    CASE
        WHEN @IsBranch = 1 THEN {Order}.[Branch] 
        ELSE 'B'
    END AS Branch

FROM {Order}
 LEFT JOIN {Item}             ON {Order}.[WasteCode]      = {Item}.[ItemCode]
                             AND {Order}.[DBId]           = {Item}.[DBId]
 LEFT JOIN {ContainerType}    ON {Order}.[ContainerCode]  = {ContainerType}.[ItemCode]
                             AND {Order}.[DBId]           = {ContainerType}.[DBId]                             
 LEFT JOIN {SiteAddress}      ON {Order}.[SiteAddress]    = {SiteAddress}.[Address]
INNER JOIN {BusinessPartner}  ON {SiteAddress}.[CardCode] = {BusinessPartner}.[Id] 
                             AND {Order}.[CardCode]       = {BusinessPartner}.[CardCode]
 LEFT JOIN {SitePlanningArea} ON {SiteAddress}.[Id]       = {SitePlanningArea}.[SiteAddressId]
WHERE {Order}.[AssignedDate]      >= @StartDate
  AND {Order}.[AssignedDate]      <= @EndDate
  AND {Order}.[RouteCode]         <> @Empty
  AND {Order}.[Scheduled]          = 1
  AND {Order}.[OrderStatusId]      = @New
  AND ({Order}.[OrderStatusId]     = @Parked OR @IsParked = 0)
  AND ({Item}.[ItemGroup]          IN (SELECT {WasteGroup}.[ItemGroup]
                                         FROM {WasteGroup}
                                        WHERE {WasteGroup}.[WasteType] = @WasteTypeId) OR @WasteTypeId = 0)
  AND ({ContainerType}.[ItemGroup] IN (SELECT {ContainerGroup}.[ItemGroup]
                                         FROM {ContainerGroup}
                                        WHERE {ContainerGroup}.[ContainerType] = @ContainerTypeId) OR @ContainerTypeId = 0)
  AND ({Order}.[RouteCode] LIKE '%' || @Search || '%' OR @Search = @Empty)
  AND ({SitePlanningArea}.[PlanningAreaId] = @PlanningAreaId OR @PlanningAreaId = 0)
  AND ((@IsBranch = 1  AND {Order}.[Branch] IN (@BranchInClause) OR {Order}.[TipName] IN (@TipNameInClause)) OR @IsBranch = 0)     
GROUP BY {Order}.[AssignedDate], {Order}.[RouteCode], Branch
UNION
SELECT 
    {Order}.[ParkedDate]        AssignedDate,
    {Order}.[ParkedCode]        RouteCode,
    COUNT({Order}.[Sequence])   Seq,
    CASE
        WHEN @IsBranch = 1 THEN {Order}.[Branch] 
        ELSE 'B'
    END AS Branch

FROM {Order}
 LEFT JOIN {Item}             ON {Order}.[WasteCode]      = {Item}.[ItemCode]
                             AND {Order}.[DBId]           = {Item}.[DBId]
 LEFT JOIN {ContainerType}    ON {Order}.[ContainerCode]  = {ContainerType}.[ItemCode]
                             AND {Order}.[DBId]           = {ContainerType}.[DBId]                             
 LEFT JOIN {SiteAddress}      ON {Order}.[SiteAddress]    = {SiteAddress}.[Address]
INNER JOIN {BusinessPartner}  ON {SiteAddress}.[CardCode] = {BusinessPartner}.[Id] 
                             AND {Order}.[CardCode]       = {BusinessPartner}.[CardCode]
 LEFT JOIN {SitePlanningArea} ON {SiteAddress}.[Id]       = {SitePlanningArea}.[SiteAddressId]
WHERE {Order}.[ParkedDate]        >= @StartDate
  AND {Order}.[ParkedDate]        <= @EndDate
  AND {Order}.[ParkedCode]        <> @Empty
  AND {Order}.[OrderStatusId]      = @Parked
  AND ({Item}.[ItemGroup]          IN (SELECT {WasteGroup}.[ItemGroup]
                                         FROM {WasteGroup}
                                        WHERE {WasteGroup}.[WasteType] = @WasteTypeId) OR @WasteTypeId = 0)
  AND ({ContainerType}.[ItemGroup] IN (SELECT {ContainerGroup}.[ItemGroup]
                                         FROM {ContainerGroup}
                                        WHERE {ContainerGroup}.[ContainerType] = @ContainerTypeId) OR @ContainerTypeId = 0)
  AND ({Order}.[RouteCode] like '%' || @Search || '%' OR @Search = @Empty)
  AND ({SitePlanningArea}.[PlanningAreaId] = @PlanningAreaId OR @PlanningAreaId = 0)
  AND ((@IsBranch = 1  AND {Order}.[Branch] IN (@BranchInClause) OR {Order}.[TipName] IN (@TipNameInClause)) OR @IsBranch = 0)  
GROUP BY {Order}.[ParkedDate], {Order}.[ParkedCode], Branch

ORDER BY AssignedDate, Branch