ODBC SQL question

Hi

I'm running PostgreSQL v6.4.2 on Red Hat Linux 6.0. I use it on a Windows NT
server 4.0 with service pack 5 through ODBC calls; the ODBC driver is the
one from Insight Distributions System, v6.40.00.06.

Usually everything is fine. My datasource works, as I can link tables from
MS Access 97 without problems.

Here is what I don't understand:
Query1: SELECT * FROM sites WHERE free = FALSE;
Query2: SELECT * FROM sites WHERE free IS FALSE;

When I run them within psql, both queries output the requested rows.

Through the ODBC driver, query1 complains that "ERROR: There is more one
possible operator '=' for types 'bool' and 'int4' You will have to retype
this query using an explicit cast (#1)

query2 complains for "Invalid use of Is operator in query expression 'free
IS FALSE'"

I tried fiddling with the ODBC driver parameters, to no avail. What do I do
wrong? I ran the queries with MS Access 97 and also with pgAdmin 6.4.3 beta,
they both return the same errors. Anybody could help me?

Here is the table definition:
+---------------------+--------------+-------+
|       Field         |     Type     | Length|
+---------------------+--------------+-------+
| site_id             | int4         |     4 |
| name                | varchar()    |    50 |
| ip                  | varchar()    |    15 |
| parent              | int4         |     4 |
| type                | int4         |     4 |
| owner               | int4         |     4 |
| admin               | int4         |     4 |
| creation_date       | datetime     |     8 |
| non_profit          | bool         |     1 |
| free                | bool         |     1 |
| reg_fee             | bool         |     1 |
| bill_period         | int2         |     2 |
| bill_date           | datetime     |     8 |
| bill_paid           | bool         |     1 |
| paid_until          | datetime     |     8 |
| size                | int4         |     4 |
| peek                | int4         |     4 |
| list_personal       | bool         |     1 |
| list_organisation   | bool         |     1 |
| list_business       | bool         |     1 |
| title_fr            | varchar()    |    75 |
| title_en            | varchar()    |    50 |
| description_fr      | varchar()    |   254 |
| description_en      | varchar()    |   254 |
| free2               | bool         |     1 |
+---------------------+--------------+-------+

Accept my apologies if I'm not in the right place to ask this. If this is
the case, please tell me where I should direct my question.

Thanks,

Nicolas Cadou