Thanks Jameson, that almost fixed it! However, there still is a difference between this new report and the standard reports.. And I have no clue why..
Tried adding DateTime from both tables just to see the intervals are the same - and they are.
Data from the new report:
Data from another (correct) report:
Jameson,
Thank you very much!
The query above showed really weird results on every metric, so I decided to go for summarizing CTSG and CTI in sub-queries and it solved everything. 
Thank you so much for your help, you saved the day (as always)
Here´s the query in case anyone needs it.
SELECT
CT.EnterpriseName as EnterpriseName,
CTSG.DateTime as DateTime,
SUM(CTI.CallsOffered) as CallsOffered,
SUM(isnull(CTSG.AnswerWaitTime,0))/ sum(isnull(CTSG.CallsAnswered,0)) as ASA,
SUM(isnull(CTSG.AnswerWaitTime,0)) as AnswerWaitTime,
SUM(isnull(CTSG.CallsAnswered,0)) as CallsAnswered
FROM
(Select
DateTime= DateTime,
CallTypeID= CallTypeID,
AnswerWaitTime=sum(isnull(AnswerWaitTime,0)),
CallsAnswered= sum(isnull( CallsAnswered,0)),
callsHandled= sum(isnull(CallsHandled,0)),
handleTime= sum(isnull(HandleTime,0)),
talkTime= sum(isnull(TalkTime,0)),
holdTime= sum(isnull(HoldTime,0)),
callsOfferedRouted=sum(isnull(CallsOfferedRouted,0)),
callsOfferedNotRouted=sum(isnull(CallsOfferedNotRouted,0)),
overflowOut=sum(isnull(OverflowOut,0)),
aat= sum(isnull(TalkTime,0))/ sum(isnull(CallsHandled,0)),
aht= sum(isnull(HandleTime,0))/ sum(isnull(CallsHandled,0)),
asa= sum(isnull(AnswerWaitTime,0))/ sum(isnull(CallsAnswered,0))
FROM Call_Type_SG_Interval
WHERE CallTypeID IN (:CallTypeID)
and DateTime >= :startDate
and DateTime <= :endDate
GROUP BY DateTime, CallTypeID) CTSG
LEFT JOIN Call_Type CT (nolock)
ON CT.CallTypeID = CTSG.CallTypeID
LEFT OUTER JOIN (SELECT
DateTime= DateTime,
CallTypeID,
CallsOffered=SUM(ISNULL(CallsOffered,0))
FROM Call_Type_Interval
WHERE CallTypeID IN (:CallTypeID)
and DateTime >= :startDate
and DateTime <= :endDate
GROUP BY CallTypeID, DateTime
) CTI
ON CTI.CallTypeID = CTSG.CallTypeID AND CTI.DateTime = CTSG.DateTime
WHERE CTSG.CallTypeID IN (:CallTypeID)
AND CTSG.DateTime >= :startDate
AND CTSG.DateTime <= :endDate
GROUP BY CTSG.CallTypeID, CT.EnterpriseName, CTSG.DateTime
ORDER BY CT.EnterpriseName, CTSG.DateTime
Thanks man, it worked! Got the correct number of CallsOffered now
It doesnt seem like its working to add any columns from ASGI table to the top though, getting errors like this:
Create the parameters or correct the query syntax and recreate the parameters. The multi-part identifier "ASGI.BusyOtherTime" could not be bound.
Here´s my current query (will do the ACW, AHT, ATT calculations later)
SELECT
CT.EnterpriseName as EnterpriseName,
CTSG.DateTime as DateTime,
SUM(CTI.CallsOffered) as CallsOffered,
SUM(isnull(CTSG.AnswerWaitTime,0))/ sum(isnull(CTSG.CallsAnswered,0)) as ASA,
SUM(isnull(CTSG.AnswerWaitTime,0)) as AnswerWaitTime,
SUM(isnull(CTSG.CallsAnswered,0)) as CallsAnswered,
SUM(ISNULL(CTSG.CallsAnswered, 0)) as ACW,
SUM(ISNULL(CTSG.CallsAnswered, 0)) as ATT,
SUM(ISNULL(CTSG.CallsAnswered, 0)) as AHT,
SUM(ISNULL(ASGI.BusyOtherTime,0)) as BusyOtherTime,
SUM(ISNULL(ASGI.WorkReadyTime ,0)) as WorkReadyTime ,
SUM(ISNULL(ASGI.WorkNotReadyTime ,0)) as WorkNotReadyTime ,
SUM(ISNULL(ASGI.ReservedStateTime,0)) as ReservedStateTime,
--SUM(ISNULL(AI.AvailTime,0)) as AvailTime, --will add later
SUM(ISNULL(ASGI.TalkInTime,0) ) as TalkInTime,
SUM(ISNULL(ASGI.HoldTime,0)) as HoldTime
FROM
(SELECT
DateTime= Call_Type_SG_Interval.DateTime,
CallTypeID= CallTypeID,
AnswerWaitTime=sum(isnull(AnswerWaitTime,0)),
CallsAnswered= sum(isnull( CallsAnswered,0)),
callsHandled= sum(isnull(CallsHandled,0)),
handleTime= sum(isnull(HandleTime,0)),
talkTime= sum(isnull(TalkTime,0)),
callsOfferedRouted=sum(isnull(CallsOfferedRouted,0)),
callsOfferedNotRouted=sum(isnull(CallsOfferedNotRouted,0)),
overflowOut=sum(isnull(OverflowOut,0)),
att= sum(isnull(TalkTime,0))/ sum(isnull(CallsHandled,0)),
aht= sum(isnull(HandleTime,0))/ sum(isnull(CallsHandled,0)),
asa= sum(isnull(AnswerWaitTime,0))/ sum(isnull(CallsAnswered,0))
FROM Call_Type_SG_Interval
LEFT OUTER JOIN (SELECT
SkillGroupSkillTargetID,
DateTime= DateTime,
WorkNotReadyTime = SUM(ISNULL(WorkNotReadyTime,0)),
WorkReadyTime = SUM(ISNULL(WorkReadyTime,0)),
TalkInTime = SUM(ISNULL(TalkInTime,0)),
TalkOutTime= SUM(ISNULL(TalkOutTime,0)),
AgentOutCalls= SUM(ISNULL(AgentOutCalls,0)),
AvailTime= SUM(ISNULL(AvailTime,0)),
HoldTime = SUM(ISNULL(HoldTime,0)),
BusyOtherTime= SUM(ISNULL(BusyOtherTime,0)),
ReservedStateTime = SUM(ISNULL(ReservedStateTime,0))
FROM Agent_Skill_Group_Interval
WHERE DateTime >= :startDate
and DateTime <= :endDate
GROUP BY SkillGroupSkillTargetID, DateTime
) ASGI
ON ASGI.SkillGroupSkillTargetID = Call_Type_SG_Interval.SkillGroupSkillTargetID AND ASGI.DateTime = Call_Type_SG_Interval.DateTime
WHERE CallTypeID IN (:CallTypeID)
and Call_Type_SG_Interval.DateTime >= :startDate
and Call_Type_SG_Interval.DateTime <= :endDate
GROUP BY Call_Type_SG_Interval.DateTime, CallTypeID
) CTSG
LEFT JOIN Call_Type CT (nolock)
ON CT.CallTypeID = CTSG.CallTypeID
LEFT OUTER JOIN (SELECT
DateTime= DateTime,
CallTypeID,
CallsOffered=SUM(ISNULL(CallsOffered,0)),
TalkTime = SUM(isnull(TalkTime,0)),
HoldTime = SUM(isnull(HoldTime,0))
FROM Call_Type_Interval
GROUP BY CallTypeID, DateTime
) CTI
ON CTI.CallTypeID = CTSG.CallTypeID AND CTI.DateTime = CTSG.DateTime
WHERE CTSG.CallTypeID IN (:CallTypeID)
AND CTSG.DateTime >= :startDate
AND CTSG.DateTime <= :endDate
GROUP BY CTSG.CallTypeID, CT.EnterpriseName, CTSG.DateTime, CTSG.DateTime
ORDER BY CT.EnterpriseName, CTSG.DateTime
