WHERE boolean = true -> failure

Hi again,
as I said I am using Access as a front-end for postgresql via ODBC.

There seams to be a problem with the boolean field. I am not able to use a
WHERE operator.
If I try to compare booleans the by example "true" - I get the following
error message:

- ODBC-call abortive

I am quit sure that I use Boolean in database and I set Boolean not as char
in the ODBC-driver.

E. Zorn