Multiple Primary Keys

Currently I have a table on Microsoft Sequel Server that I wish to port over to Postgresql.   This table has four primary keys and it's the combination of the four fields that make the record unique.  I have created the table in Postgresql using this in my create.

CONSTRAINT "attachments_pkey"   PRIMARY KEY ("docn","issue","docna","issuea"));"

The table gets created with four primary keys, but when I copy in the data I get the following error..

"Cannot insert a duplicate key into unique index attachments_pkey"

Any ideas??

Debra Samsom
Senior Business Systems Analyst
Bristol Aerospace Ltd.
(204) 775-8331 3402
dsamsom@bristol.ca