Timestamp without timezone

I'm using Microsoft Visual Foxpro 9 developing an ERP application,
using PostgreSQL 8.2.5 and ODBC connection in version 7.

If I upgrade my ODBC drivers to use "PostgreSQL ANSI", becomes an
error like this:

"function saldo_estoque("unknown", "unknown", "unknown", "unknown",
timestamp without time zone) does not exist"

However, the "unknown" types are BPCHAR on function "saldo_estoque",
and "timestamp without time zone" is DATE type.

How can I solve this?