Default values error: "input required"

My PostgreSQL database contains a table My_Table featuring (among others) a
column "entry_created_on" as date, and a column "entry_created_by" as text.

The default value of "entry_created_on" is: now()
and the default value of "entry_created_by" is: "current_user"()

I use OpenOfficeBase (similar to MsAccess) as a front-end to populate the
database through the JDBC driver. One of these forms deals with My_Table.
I left out of the form any reference to "entry_created_on" and
"entry_created_by", with the impression that the postmaster would provide
those columns with their default values whenever a new entry was added to
the table---which is exactly what I would like to see happening.

Instead, OOoBase throws the follow error message:
"Error writing data to database. Input required in field 'entry_created_on'.
Please enter a value."

On the other hand, everything works fine when I created a new row through an
sql INSERT command, or through pgAdmin: I get the expected defaults values
of now() and "current_user"().

Is the problem with the JDBC driver or is it with OOoBase? Does a similar
situation occur with MsAccess? Have I forgotten something obvious?

PS: I tried using the SDBC driver, but OOoBase doesn't see the content of my
tables, only their structure and the number of rows. I also tried with the
ODBC driver, but I was even less successful, since I couldn't even see my
schemas and tables, even though the driver claims to connect properly...

PPS: I was undecided where to send this; sorry if this issue was more
appropriate to the Interface list!