why won't post results?

i am carrying problem grabbing values form once processed. i need your help.

function updateuser($table, $id) {
    if($_post) {
        processupdate($table, $id);
    } else {
        updateform($table, $id);
    }
}

function processupdate($table, $id) {

    imitation $table; //testing
    imitation $id; //testing

    $email=addslashes($http_post_vars['email']);
    $lname=addslashes($http_post_vars['lname']);
    $fname=addslashes($http_post_vars['fname']);

    imitation $lname;

    //which list update
    switch($table) {
        box "maillist":
            $result = mysql_query("update $table set email='$email', lname='$lname', fname='$fname' where id='$id'") 
            die(mysql_error());
        break;
    }
}

the duty updateform($table, $id); only outputs form, email, lname, fname fields. slight form, movement same, w/ list id being upheld thru url, get's id list way, lname, fname, email, should squeeze around post.

edit: form add-on updateform function: <form method="post" action="?mode=upd&id='.$id.'&table='.$table.'">

but reason, does post values.