One of our customer reports: Ora-01480 - Trailing null missing from STR bind value. (Ora10 database, delphi7, doa 4.0.6.2)

It happens on a update from a normal oracledataset. The size of the field in de database en tstringfield is 2000. The length of the string being inserterd is approximatly 1100 characters. What could be the problem?

Oracle monitor query generated:
update AROOSTERPLOEG
set ARP_DIENSTEN = :v1
where rowid = :doa__rowid
returning rowid into :doa__rowid