error Shout Box

[miguemangu]

te un mini chat que se llama shout box y cuando escribe sale Database error 24.porque es?
el archivo de base d datos es es te:
<?php
function init_shoutbox_table()
{
global $dbconn;
$strSQL = "CREATE TABLE IF NOT EXISTS " . SHOUTS_TABLE . "
(
id int(11) NOT NULL auto_increment,
user_id int(11) NOT NULL DEFAULT '0' ,
text varchar(250) NOT NULL DEFAULT '' ,
date_add datetime NOT NULL DEFAULT '0000-00-00 00:00:00' ,
PRIMARY KEY (id)
)";
$rs = $dbconn->Execute($strSQL);
if ($rs === false)
{
print ("<br>\nError: Database error.<br>\nError file: " . __file__ . "<br>\nError file line: " . __line__);
exit();
}
$rs = $dbconn->Execute("INSERT INTO " . SHOUTS_TABLE . " VALUES (4, 17, 'Hello all!', '2007-07-06 15:34:04') ");
$rs = $dbconn->Execute("INSERT INTO " . SHOUTS_TABLE . " VALUES (5, 6, 'Welcome to our community!', '2007-07-06 15:35:55') ");
$rs = $dbconn->Execute("INSERT INTO " . SHOUTS_TABLE . " VALUES (6, 20, 'I like it there!', '2007-07-06 17:36:04') ");
$rs = $dbconn->Execute("INSERT INTO " . SHOUTS_TABLE . " VALUES (7, 15, 'Come to chat!', '2007-07-06 17:37:17') ");
return 0;
}
?>