I need some help with this SQL

SELECT T.RECID, X.SHORTNAME, T.AMNT, T.TRNID, T.TRNTYPE, Sum(T.AMNT) as
TotalAmnt
from crtbp T
left outer join trntype X ON (X.RECID = T.TRNTYPE)
where T.AMNT <> 0
GROUP BY T.TRNID
ORDER BY T.TRNID ASC

What I am trying to do is for each unique TRNID, find the sum of the float
field AMNT but my SQL results in an "invalid column reference"

Thanks for any help.
jackie