Referential Integrity problem - Mailing list pgsql-general

I hope this one is just some misunderstanding on my part.

I have a table structure like so (scroll down for executive summary):

create table common (
        createdate timestamp default current_timestamp,
        modifydate timestamp default current_timestamp,
        syncdate timestamp default '1900-01-01'
);

create table saleable_item (
        id serial primary key,
        sale_id integer references sale,
        stock integer default 0,
        baseprice float default 0.00
) inherits (common);

create table product (
        title_id integer references title,
        format_id integer references format
) inherits (saleable_item);

create table chart (
        id serial primary key,
        name text
) inherits (common);

create table chartitem (
        id serial primary key,
        chart_id integer references chart,
        position integer,
        product_id integer references saleable_item
) inherits (common);

That's the minimum I can show you to demonstrate this unfortunately. So,
there is a product table that inherits a saleable_item table,
saleable_item defines fields relating to stuff that you'd sell (products
is a poorly named table, but it's for historical reasons). saleable_item
in turn inherits from common - which defines some fields I need to store
about every record - in particular information to help me syncronise
this database with another one.

The chart and chartitem table are meant to represent listings of
products or rather, saleable_items that my client wants to draw
attention to. So you put an entry into chart to give this collection of
products a descriptive name, and then each item in the chart refers to
this chart by its ID.

Here's the problem:

# insert into chartitem (chart_id, position, product_id) values
(1073741826, 1, 1073741827);
ERROR:  $2 referential integrity violation - key referenced from
chartitem not found in saleable_item

the product ID does exist:

# select id from product where id = 1073741827;
     id
------------
 1073741827
(1 row)

And of course it exists in saleable_item as well (since that is where
the ID field is inherited from).

Now I assume that something has gone wrong in inheriting the primary key
- is there anything I'm missing? I'm sure I've done this sort of thing
before.

# select version();

version
--------------------------------------------------------------------------------------------------------
 PostgreSQL 7.3.2 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 3.2.1
(Mandrake Linux 9.1 3.2.1-7mdk)
(1 row)

Many thanks,

James.