COPY from on date field problem

Pg ver: 7.2
I'm trying to do a COPY function from a tab delimited file into a table
defined as such:

CREATE TABLE "mdc_priceschedule" (
"keyp_price" int4 NOT NULL,
"keyf_products" int4 NOT NULL,
"date_start" date ,
"date_end" date ,
"price_normal" numeric(13, 2) ,
"inc_event_type" int2 ,
"sale_value" numeric(13, 2) ,
"price_sale" numeric(13, 2) ,
CONSTRAINT "xpkmdc_priceschedule" UNIQUE ("keyp_price")
) WITH OIDS;

record example:
112116 73440 2/9/2002 2/9/2007 49 2 0 .01
112117 73017 1/7/2002 12/7/2006 189 2 0 65.99
112118 73450 0 0 0 0
112119 73016 1/7/2002 12/6/2006 69 2 0 23.99

Some of the date fields and numeric fields maybe a NULL value. However,
whenever I try to import any record that may have a NULL value in the
date_start field for example, I get a message stating Bad date external
representation ''.
Any clue why this would happen?
Just a FYI, I have tried putting DEFAULT NULL on the date fields, but Pg
keeps removing them. I assume that this means NULL is a default.

TIA

Patrick Hatcher
Macys.Com
Legacy Integration Developer
415-932-0610 office