problems with pgsql and jbuilder (jdbc)

hi everybody again, i were trying to post this to the jdbc newsgroups,
but it seems to be
unavailable, sorry

we're developing a payroll application using jbuilder and between it's
goals
are database independence, so we're testing it with the most popular
databases
(at least in our area): postgresql, oracle, sqlserver

recently i've getting some weird messages when trying to update data
involving
numeric values in postgresql, the error is:

 Unable to identify an operator '='for types 'numeric' and 'float8'
 You have to retype this query using an explicit cast

when the data is entered for the first time, everything is ok, but as
previuosly
said, the problem raises when trying to do an update

in one example i'm using a jdbtable (borland dataexpress component) tho
show and
update the data, the db table schema is:

              Table "zona"
  Attribute |     Type      | Modifier
 -----------+---------------+----------
  fecha_vig | timestamp     | not null
  id_zona   | numeric(1,0)  | not null
  nombre    | varchar(25)   |
  sal_min   | numeric(10,2) |
 Index: zona_pkey


to update the content, the user captures the new value in the
corresponding
jdbtable cell, and in a jdbnavtoolbar presses the post and save buttons,
i'm
trapping the save event to do some validations, and thereafter invokes
the
saveChanges method, something like:

 dataModule11.qZona.saveChanges();

and the exceptions is thrown.

i'm thinking of a bug in the dataexpress components, because prevoiusly
i've
getting an error when using the sql max() function in a query, it takes
about
10 minutes to obtain the result, but the same query where executed in
milliseconds in a java application not builded with jbuilder

currently i'm using jbuilder 4.0 running in redhat 6.2, postgresql 7.1.3
in
redhat 7.1 and the jdbc-7.1-1.2.jar

none of this problems occurs with oracle

hope somebody can give some advice to find the problem, thanks a lot in
advance (and sorry about my english)