Error in creating Primary Key

Right out of the manual I am using the command...
CREATE TABLE distributors (
did DECIMAL(03) PRIMARY KEY DEFAULT NEXTVAL('serial'),
name VARCHAR(40) NOT NULL CHECK (name <> '')
);

Whenever I try to use a primary key, I get a message
notice: Create table/primary key will create implicit index
'distributors_pkey' for table distributors
and Worse...

ERROR: Can't find a default operator class for type 1700.

Any help would be appreciated....