Receiving GROUP BY error in Oracle 8i but not 10g

strQry = "select major,demand, head, pnp,cvt,sum(case when accountmonth < 
  " & AccMonCode & " and year = " & AccFinYear & " then amount else 0 end) 
  as uptothismonth," & _
            " sum(case when accountmonth = " & AccMonCode & " and year = 
  " & AccFinYear & " then amount else 0 end) as thismonth, " & _
            " sum(case when accountmonth <= " & AccMonCode & " and year = 
  " & AccFinYear & " then amount else 0 end) as total, " & _
            " (case when c.major >= '2011' and c.major <= '2059' then 'I' " & _
            "      when c.major >= '2070' and c.major <= '2205' then 'II' " & _
            "      when c.major >= '2210' and c.major <= '2217' then 'III' " & _
            "      when c.major >= '2220' and c.major <= '2404' then 'IV' " & _
            "      when c.major >= '2405' and c.major <= '2701' then 'V' " & _
            "      when c.major >= '2702' and c.major <= '3475' then 'VI' " & _
            "      when c.major >= '6003' and c.major <= '7610' then 'VII' " & _
            "      when c.major >= '4055' and c.major <= '4406' then 'VIII' " & _
            "      when c.major >= '4407' and c.major <= '5452' then 'IX' end) as volume, " & _
            " (SELECT distinct DetailDesc FROM Common.detail WHERE detail=substr(c.head,12,2)) as description, " & _
            " (SELECT distinct DemandDesc FROM Common.demand WHERE demand=c.demand) as demanddesc, " & _
            " (SELECT distinct majorDesc FROM Common.major WHERE major=c.major) as majordesc, " & _
            " (SELECT distinct submajorDesc FROM Common.submajor 
  WHERE major||submajor=substr(c.head,1,6)) as submajordesc, " & _
            " (SELECT distinct minorDesc FROM Common.minor 
  WHERE major||submajor||minor=substr(c.head,1,9)) as minordesc, " & _
            " (SELECT distinct subDesc FROM Common.sub 
  WHERE demand||major||submajor||minor||sub||pnp=c.demand||substr(c.head,1,11)||c.pnp) as subdesc, " & _
            " (case when substr(head,7,7) <> '0000000' then '1' else '2' end) as recovery " & _
            " from conspayments c where major < '8000' and year = 
  " & AccFinYear & " group by Head,major,Demand,PNP,CVT ORDER BY volume,major,recovery,demand,head,pnp,cvt"