在WINDOWS下用perl的DBI连接mssql问题请教！

zw1971

安装了DBI模块，
use DBI;
$dth = DBI->connect("dbi::mSQL:zw","administrator","123456")||die "can't open databaseDBI::errstr\n";
$dth->disconnect;
exit;


其中zw 为创建DSN数据源，运行程序时提示：
can't connect to data source mSQL:zw,no database driver specified
and DBI_DSN env var not  not set at 1.pl at  line 2.

请教！！