Sql with Lateral

I'm trying to only get the first record from PTIIJ00 because it has
multiple records with the same line# when matching PTIIS00. This SQL
doesn't get any PTIIJ00 row:

SELECT SDEXP01,ISSTYLEID,ISCOLORID,IJINSTR01,sum(istunits)
FROM whssd00 LEFT JOIN ptiis00 on isdid# = sddid#
left JOIN LATERAL (SELECT * from ptiij00 fetch first row only)
ON sddid# = ijdid# AND isline# = ijline
where sdexp01 >= 1234567
GROUP BY SDEXP01, ISSTYLEID, ISCOLORID, IJINSTR01
ORDER BY SDEXP01, ISSTYLEID, ISCOLORID, IJINSTR01

If I remove FETCH FIRST ROW ONLY it brings in the PTIIS00 record multiple
times and it makes my SUM(UNITS) wrong.

I can explain more detail if necessary.