primary key

I trust this query on postgresql 6.2.x



CREATE TABLE films (
       code      CHARACTER(5) CONSTRAINT firstkey PRIMARY KEY,
       title     CHARACTER VARYING(40) NOT NULL,
       did      DECIMAL(3) NOT NULL,
       date_prod DATE,
       kind     CHAR(10),
       len       INTERVAL HOUR TO MINUTE     );


but I have error near CONSTRAINT.

Maybe this version of postgres can't accept the primary key?