SSRS : Repeating table with multiple-value parameter - reporting-services

Question

I'm struggling with something which is probably easy in reporting services, but could not find any online help on this.
I'm building a telephony report for my company that show statistics for our clients. The main parameters for this report are : client name, date from, date to
Each client can have several calls queues (not the same number for each) so I need to create a statistics table that shows numbers, and repeats itself for each call queue.
I created a multi-values parameter for the queues that populates itself from this query:
SELECT queue_id FROM customers WHERE customer_name = #Customer
The subreports parameters are:
date_from = [#date_from]
date_to = [#date_to]
queueid = =Split(join(Parameters!client_call_queues.Value,","),",")
And here comes the issue, when I show the report preview, I can see the table with values, but summed for all queues, not splitted.
If I add a custom grouping on the tablix, it returns me a wrong calculation.
To go deeper in details, here's below a first printscreen that shows the numbers for all the queues:
and the table I get from the subreport, without custom grouping:
I tried to add this custom grouping, in the subreport tablix:
And here's the result it gives with that grouping:
Here's below the query used to populate subreport tablix:
SELECT
#queueid,
ISNULL(q1.[Day],'TOTAL') AS [Day],
COUNT(*) AS [Calls In],
SUM(CASE WHEN q1.[Call Type] = 'Answered Within Threshold' THEN 1 ELSE 0
END) + SUM(CASE WHEN q1.[Call Type] = 'Answered After Threshold' THEN 1 ELSE
0 END) AS [Answered],
SUM(CASE WHEN q1.[Call Type] = 'Abandoned Within Threshold' THEN 1 ELSE 0
END) AS [Abd. Within Threshold],
SUM(CASE WHEN q1.[Call Type] IN ('Abandoned Within Threshold') THEN 1 ELSE 0
END)/CONVERT(DECIMAL(10,2),COUNT(*)) AS [Calls Abandoned Within Threshold
Rate],
SUM(CASE WHEN q1.[Call Type] = 'Abandoned After Threshold' THEN 1 ELSE 0
END) AS [Abd. After Threshold],
SUM(CASE WHEN q1.[Call Type] IN ('Abandoned After Threshold') THEN 1 ELSE 0
END)/CONVERT(DECIMAL(10,2),COUNT(*)) AS [Calls Abandoned After Threshold
Rate],
SUM(CASE WHEN q1.[Call Type] = 'Voicemail' THEN 1 ELSE 0 END) AS [Voice
Mail]
FROM
(
SELECT
CUS.[Customer],
SUBSTRING(CONVERT(VARCHAR,ACD.[startdatetime],121),1,10) AS [Day],
ACD.[sessionid],
ACD.[contactdisposition],
ISNULL(ACD.[Squeuetime],0) AS [Squeuetime],
CUS.[ans_speed_secs],
CUS.[abd_tresh],
ACD.[businesshours],
ACD.[contacttype],
ISNULL(ACD.[connecttime],0) AS [connecttime],
ACD.[voicemail],
CUS.[ans_speed_rate],
ACD.[callednumber],
CUS.[Active],
ISNULL(ACD.[Stalktime], 0) AS [Stalktime],
ISNULL(ACD.[Sholdtime], 0) AS [Sholdtime],
CASE
WHEN ACD.[contactdisposition] = 2 AND ISNULL(ACD.[Squeuetime],0) <= CUS.
[ans_speed_secs] THEN 'Answered Within Threshold'
WHEN ACD.[contactdisposition] = 2 AND ISNULL(ACD.[Squeuetime],0) > CUS.
[ans_speed_secs] THEN 'Answered After Threshold'
WHEN ACD.[contactdisposition] <> 2 AND ISNULL(ACD.[Squeuetime],0) <=
CUS.[abd_tresh] THEN 'Abandoned Within Threshold'
WHEN ACD.[contactdisposition] <> 2 AND ISNULL(ACD.[Squeuetime],0) > CUS.
[abd_tresh] THEN 'Abandoned After Threshold'
WHEN ACD.[voicemail] = 'VoiceMail' THEN 'Voicemail'
END AS [Call Type]
FROM [ACD].[dbo].[UccxCallsQuery2] ACD
LEFT OUTER JOIN [ACD].[dbo].[Customers] CUS ON ACD.[callednumber] = CUS.
[Called_id]
WHERE CUS.[ACDSelection] IN (#queueid)
AND ACD.[businesshours] <> 'NBO'
AND ACD.[contacttype] = 1
AND CUS.[Active] = 1
AND CONVERT(DATE,ACD.[startdatetime]) BETWEEN #date_from AND #date_to
) q1 GROUP BY q1.[Day] WITH ROLLUP
I guess this is only a simple thing, but can spot it.
Thanks in advance for any help on this !