Postgres Table inheritance

[zydoon]

Hi all,
I do have this DB schema :
PARTS
LENSES--> inherits PARTS
SUPPLIER, and
SUPPLIER_PARTS : defining the suppliers of one kind of parts (with all due foreign keys)

now when INSERTING into SUPPLIER_PARTS it complains about abscence of the PARTS_ID, which of course exists.

on psql : when I do "select only from parts" the PARTS_ID indeed does not exist.

Is there anyway to work-around this ?