How to get Postgres in ODBC

Hi,

I'm trying to develop a C application using ODBC on PostgreSQL 7.3.1.
I link my application with the lib : libodbcpsql.so.2.0.0. But the ODBC
function SQLGetDiagRec() used to get the error message does not exist in

this lib.

Does anyone, can tell me how to get back the postgres error message
through the ODBC API.

    Thierry