Error with query

I'm still a postgres newbie so don't get upset if I'm sending this
question to the wrong forum, just tell me if I am and I'll move it.

I get this error message in Firefox:
Error with query: ERROR: invalid input syntax for type date: "" LINE
1: ..._name, pack_tidin, pack_tidut, pack_lunch) VALUES('', '', ''...
^

When running this query with PHP:

<?php
$db = pg_connect('host=localhost dbname=name user=me password=pass');

$pack_date = pg_escape_string($_POST['pack_date']);
$pack_week = pg_escape_string($_POST['pack_week']);
$pack_day = pg_escape_string($_POST['pack_day']);
$pack_pts = pg_escape_string($_POST['pack_pts']);
$pack_name = pg_escape_string($_POST['pack_name']);
$pack_tidin = pg_escape_string($_POST['pack_tidin']);
$pack_tidut = pg_escape_string($_POST['pack_tidut']);
$pack_lunch = pg_escape_string($_POST['pack_lunch']);

$query = "INSERT INTO timmar(pack_date, pack_week, pack_day, pack_pts,
pack_name, pack_tidin, pack_tidut, pack_lunch) VALUES('" . $pack_date
. "', '" . $pack_week . "', '" . $pack_day . "', '" . $pack_pts . "',
'" . $pack_name . "', '" . $pack_tidin . "', '" . $pack_tidut . "', '"
. $pack_lunch . "')";
$result = pg_query($query);
if (!$result) {
    $errormessage = pg_last_error();
    echo "Error with query: " . $errormessage;
    exit();
}
printf ("Detta har lagts till i databasen - %s %s %s", $pack_date,
$pack_week, $pack_day, $pack_pts, $pack_name, $pack_tidin,
$pack_tidut, $pack_lunch);
pg_close();
?>

I've search every little " and ' and , and . and all I can think of
but it still doesn't work. I started with only 3 columns (in another
test-database) and everything was just fine.
Anyone who can spot something I missed?

If you think you need the FORM part just let me know and I'll send it.

Regards,
Helgi Örn

--
PostgreSQL 8.4.4, Ubuntu Linux 10.04, Firefox 3.6.10