ODBC driver chances function-call in a wrong way

Hello,

I have the following problem:

I have a PG function in my database which looks like this:

CREATE OR REPLACE FUNCTION help_sel0(IN a int,IN b char(2),OUT
master_fileset INT, OUT master_type CHAR(2), OUT highest_number INT)
RETURNS RECORD AS

$function$

DECLARE

r RECORD;

BEGIN

SELECT INTO r
master_fileset,master_type,highest_number

FROM gen_master

WHERE master_fileset= a

AND master_type= b;

master_fileset:=r.master_fileset;

master_type:=r.master_type;

highest_number:=r.highest_number;

END;

$function$

LANGUAGE plpgsql;

When I now want to send with my ODBC-programm the following prepared
statement to the server

{SELECT * FROM gen_master_sel0(?,?);} (with the parameters 10 and 'S2')

the driver recognizes that I'm calling a "stored procedure", but he
doesn't notice the given parameter and changes the command to this

SELECT * FROM gen_master_sel0( 10, E'S2');() .

Is this a bug in the recent driver (8.3.0400) which I'm using or has
anybody any idea what I might have done wrong? I have to say this is the
first time I'm working with Postgres so maybe my function is not ok?!

I'm very thankful for ideas and suggestions :-)

Thx, Ida