when my program run to 
$h = dba_open("test.db2", "c", "db2", 0666);
it reported Warning: no such handler: db2 in ......

my configure line:
./configure --with-mysql --with-db2 --with-apache=../apache_1.3.9 --enable-track-vars

My program:
<?php
error_reporting(15);

        $h = dba_open("test.db2", "c", "db2", 0666);
        if(!$h)
                die("cannot open db\n");
        for($i=0;$i<10;$i++)
            dba_replace("bate_$i", "$i", $h);
        dba_optimize($h);
        dba_close($h);
        $h = dba_open("test.db2", "r", "db2");
        if(!$h)
                die("cannot open db\n");
        for($key=dba_firstkey($h);$key != false;$key=dba_nextkey($h))
            echo "**".$key."**";
        dba_close($h);
?>