Para mim, isso parece uma tentativa fracassada de subdigitação. Isso é o que eu acho que você tem agora.
Com base no modelo, o seguinte deve funcionar:
;
with
q_00 as (
select
pa.Deal_Id as Deal_Id
, coalesce(sp.BROJ_TIKETA, fw.BROJ_TIKETA, sw.tiket, ia.BROJ_TIKETA, '') as Ticket_No
, coalesce(sp.Trans_Id, fw.Trans_Id, sw.Trans_Id, ia.Trans_Id) as Trans_Id
from #PotencijalniAktuelni as pa
left join kplus_sp as sp on sp.sp_Id = pa.Deal_Id and pa.KplusTable_Id = 1
left join kplus_fw as fw on fw.fw_Id = pa.Deal_Id and pa.KplusTable_Id = 2
left join dev_sw as sw on sw.sw_Id = pa.Deal_Id and pa.KplusTable_Id = 3
left join kplus_ia as ia on ia.ia_Id = pa.Deal_Id and pa.KplusTable_Id = 4
)
select
Deal_Id
, max(Trans_Id) as TransId_CurrentMax
into #MaxRazlicitOdNull
from q_00
where Ticket_No <> ''
group by Deal_Id ;
SQL Server 2005+