Unknown connect option while using IDL

Hi all,
I'm a newbie to PostgreSQL and ODBC, so I hope this question is not
too stupid....
We're using a tool for data analysis called IDL (nothing in common with
Corba, btw.). It offers a ODBC interface. When trying a connection I get an
error:

IDL> objDB = OBJ_NEW('IDLdbDatabase')
% Loaded DLM: DATAMINER.
IDL> objDB->Connect,datasource='PostgreSQL'
% IDLDBDATABASE::CONNECT: ODBC Unknown connect option (Set)
% Execution halted at: $MAIN$
This occurs when using both, the libpsqlodbc.so from PostgreSQL 7.1.3 and
7.2b2.
The package unixODBC (www.unixodbc.org) also contains a version of the
PostgreSQL driver. When specifying this lib in .odbc.ini, the error above
does *not* occur. But I can't use this driver because it limits the maximum
length of text fields.
The .odbc.ini used is:
<snip>
[ODBC Data Sources]
PostgreSQL=PostgreSQL 7.1.3

[PostgreSQL]
Driver=/home/stefan/packages/postgresql-7.2b2/src/interfaces/odbc/libpsqlodbc.so
Description = PostgreSQL
Database = testdb
Servername = db01
UserName = bi
Password = pw

[ODBC]
Trace=1
TraceFile=odbctrace.out
TraceDll=/home/stefan/packages/idl/idl_5.5/bin/bin.linux.x86/dm/lib/odbctrac.so
InstallDir=/home/stefan/packages/idl/idl_5.5/bin/bin.linux.x86/dm
</snip>
The tracefile "odbctrace.out" is attached.
So I need a driver that does not cause the error above and is capable of
handling large text fields.

Thanks in advance
Stefan