dbi perl and DBINFO

I'm trying to obtain the last serial value after an insert, in a Perl DBI script. I see that DBINFO('sqlca.sqlerrd1') sometimes returns '0' in this script. Using SE Informix 7.24UC8 with perl 5.6. It doesn't happen very often, usually the select DBINFO('sqlca.sqlerrd1') works OK and returns the last serial inserted. I now removed the DBINFO's and I'm trying via $sth->{ix_sqlerrd}[1] as the manpage suggests (this is better anyway), but shouldnt' the DBINFO also work ?