cant create index on decimal column

Hi I have a problem. I cant create indexes on decimal columns.

CREATE TABLE REQUIREMENT_COST(
 WORKORDER_TYPE CHAR(1) NOT NULL,
 WORKORDER_BASE_ID VARCHAR(30) NOT NULL,
 WORKORDER_LOT_ID VARCHAR(3) NOT NULL,
 WORKORDER_SPLIT_ID VARCHAR(3) NOT NULL,
 WORKORDER_SUB_ID VARCHAR(3) NOT NULL,
 OPERATION_SEQ_NO SMALLINT NOT NULL,
 REQ_PIECE_NO SMALLINT NOT NULL,
 QTY DECIMAL(14,4) NOT NULL,
 UNIT_COST DECIMAL(14,4) NOT NULL,
 FIXED_COST DECIMAL(15,2) NOT NULL,
 MINIMUM_COST DECIMAL(15,2),
 PRIMARY

KEY(WORKORDER_TYPE,WORKORDER_BASE_ID,WORKORDER_LOT_ID,WORKORDER_SPLIT_ID,WORKORDER_SUB_ID,OPERATION_SEQ_NO,REQ_PIECE_NO,QTY
))
;
NOTICE:  CREATE TABLE/PRIMARY KEY will create implicit index 'requirement_cost_pkey'
for table 'requirement_cost'
ERROR:  Can't find a default operator class for type 1700.

If the field qty is deleted from the above primary key the create works.
I assume that there is an operator I can add to fix this?

bob

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