can not insert into table using perl/DBI to InnoDB type database

[Haifang Wang]

Dear Support Team,
Now I am using Perl/DBI to interface with mysql database, and my all my tables were created using engine=InnoDB. I can not insert data using the following script in perl:
my $sql1=qq{insert into gene values (null,"1000","testing")};
$dbh->do($sql1);

PS: the first line of table gene is auto-increment.