GL_DATE Problem

I export a database from a Unix server (7.31-UC5) using the GL_DATE=%d/%m/%Y. Then I import this database on an NT server with service pack 5 or 6. The Informix version is 7.31-TC6 and GL_DATE=%d/%m/%Y. While importing I get the error 1205 (Invalid month in date). When I change the enviroment variable to DBDATE=DMY4/ the database is imported successfully. After the database is imported I open a dbaccess session with GL_DATE=%d/%m/%Y. The dates are in the format mm/dd/yyyy when I execute select queries. The export (unl file) had the date as dd/mm/yyyy. When I set the enviroment variable DBDATE=DMY4/ the date is correct (dd/mm/yyyy). Any ideas how to import the database using the GL_DATE instead of DBDATE? Vasilis