MySQL not qorking

[Acidic]

OK. why does this not work:

$a = $_SERVER['REMOTE_ADDR']." - ".$_SERVER['HTTP_USER_AGENT']." - ".$_SERVER['REMOTE_PORT'];
echo $a."<br />";
$result = mysql_query("INSERT INTO `jchat` (`id`, `message`, `loginid`) VALUES ('', '".$a."', ''");
echo $result; 

I've used the same code on my localhost where it worked, but on the server it does nothing.

It echo's $a fine, but nothing gets done to the database, I get no errors and the database/table do definately exist.

I realise that the names of the fields on the mysql statement seem weird, and that I'm not using 2 of them, but this is only a temporary test thing, so I don't want to make a new table as I don't have permissions to delete them, only to create them.