An aggregate may not appear in the WHERE clause unless it is in a subquery contained

1 

   select * into #tempL
  from
  (SELECT  [PGroup_strCode]
      ,[Price_strCode]
      ,[Price_intSequence]
      ,[Price_curPrice]
      ,[STax_strCode]
      ,[Price_strDescription]
      ,[Price_strShortDesc]
      ,[Price_strPackage]
      ,[Price_intPackageQuantity]
  FROM [tblPrice]
  where  Price_strDescription not like '*%'


) as t;


with tickets
(GrossValue,transnumber,cinema,fullprice,sequence)
as(select T.GrossValue,t.TransNumber,t.CinemaCode, TMP.Price_curPrice,T.TransSequence from tblDWTicket T 
  inner join #tempL TMP on t.PriceGroup=TMP.PGroup_strCode and T.PriceCode = TMP.Price_strCode
    where T.SalesTransDate > '20180616' and T.TransStatus not in ('C','R') and T.TransType = 'TKT'
	and T.SalesTransWorkstationCode like 'K%'
--	group by T.GrossValue,T.TransNumber,T.CinemaCode,TMP.Price_curPrice,T.TransSequence
  )



  select  tickets.GrossValue,tickets.transnumber,tickets.cinema,tickets.fullprice, F.GrossValue as Value
  ,tickets.sequence from tickets
  left join tblDWBookingFee F on tickets.Transnumber = F.Transnumber and tickets.cinema= F.CinemaCode
   where tickets.GrossValue + IsNull(sum(F.GrossValue), 0) <> fullprice
 -- group by tickets.GrossValue,tickets.transnumber,tickets.cinema,tickets.fullprice,tickets.sequence

  

  drop table #tempL

Hi.
I would like to find any tickets that have a different full price, compared to tickets.GrossValue + F.GrossValue
but I get "An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference."
I'm currently reading that I need an inner select to fix that but I'm not sure. Do i need to re select the entire booking and ticket?
thanks