Error with select statement

Hello Everybody

The following sql command runs into an error(maxdb7.6):

(i removed the columns from the left joined tables from the select list to make it clearer)

select

substr(rbkontakt.rbkontakttext,1,254) as incident,

substr(rbkontakt.rbkontakttext,255,254) as incident2,

substr(rbkontakt.rbkontakttext,509,254) as incident3

from RBKONTAKT

join rbobjekte on rbkontakt.rbobjekteid = rbobjekte.rbobjekteid

left join stnlstamm on rbkontakt.stnlstammid = stnlstamm.stnlstammid

left join stauftragsstamm on rbkontakt.stauftragsstammid = stauftragsstamm.stauftragsstammid

left join stnlstamm as nlstamm on rbkontakt.stnlstammidabr = nlstamm.stnlstammid

left join rbkontaktmassnahmen on rbkontakt.rbkontaktid = rbkontaktmassnahmen.rbkontaktid

where rbkontakt.projekt = 'COBAMITTESUED'

-

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Error -

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Auto Commit: On, SQL Mode: Internal, Isolation Level: Committed

Syntax error or access violation;-2000 POS(9027) Row too long

incident is varchar(1000)

The same command works against another table with an varchar(1000) column????

The same command works with join instead of left join ????

Any help welcomed

Best regards

Albert