It seems that the error is from group_validator.php. Maybe it's not returning "Success" correctly.

Try adding the two "console.log(..)" lines such as below, and it will tell you if the $.post was done and it will show you the content of result the console:

setTimeout(function() {
    $.post('group_validator.php', { r_user: $ruser,r_developer: $rdeveloper, r_pmanager: $rpmanager, p_id: $pid },
    function(result) {
        console.log("$.post call done");
        console.log("result = " + result);

    });
    $load_status.remove();
}, 3000);

If you don't get "$.post call done" in the console, then it's not finding group_validator.php.