Adding points upon giving a rank - php

Question

Right so i have a promotion button setup. Every promotion someone receives it gives them earning points to their profile, But every rank has different points depending on how high it is or low it is. I'm having a hard time trying to figure out how to get the points to scale with their ranks. My database column for it is known as: rank and the ranks are known as numbers in the database in which when it shows externally they all have a name from a function. So ie; Rank 1, 2, 3, 4 would equal say Noob, Member, Elite, God. Anyway if you can help me find out where my error is that would be great, kinda new to php. The issue I'm having is that the points are not being given to the person. They get promoted fine but no points.
promote.php
<?php include_once('../classes/check.class.php'); ?>
<?php include('../config/db.php'); ?>
<?php include('functionsprom.php'); ?>
<?php if( protectThis("1, 2, 3") ) : ?>
<?php
if (isset($_GET['id']) && is_numeric($_GET['id']))
{
$id = $_GET['id'];
$date = date('d M y');
$prom = promote;
$result = mysql_query("UPDATE players SET date='$date', rank = rank + 1, exp = exp + '$prom' WHERE id=$id", $db1)
or die(mysql_error());
require_once("../config/logdb.php");
include('../logs.php');
write_mysql_log($promote, $db);
header("Location: ../home.php");
}
else
{
header("Location: home.php");
}
?>
<?php endif; ?>
functionsprom.php
<?php
include('functionsrank.php');
mysql_select_db('pts_player');
$rank = "SELECT rank FROM players WHERE id = $id";
function promote($rank) {
if($rank == 1):
$prom = 0;
elseif($rank == 2):
$prom = 0;
elseif($rank == 3):
$prom = 0;
elseif($rank == 4 ):
$prom = 10;
elseif($rank == 5):
$prom = 20;
elseif($rank == 6):
$prom = 30;
elseif($rank == 7):
$prom = 45;
elseif($rank == 8):
$prom = 45;
elseif($rank == 9):
$prom = 55;
elseif($rank == 10):
$prom = 60;
elseif($rank == 11):
$prom = 75;
elseif($rank == 12):
$prom = 75;
elseif($rank == 13):
$prom = 0;
elseif($rank == 14):
$prom = 0;
elseif($rank == 15):
$prom = 100;
elseif($rank == 16):
$prom = 200;
elseif($rank == 17):
$prom = 400;
elseif($rank == 18):
$prom = 600;
elseif($rank == 19):
$prom = 800;
elseif($rank == 20):
$prom = 900;
elseif($rank == 21):
$prom = 1000;
elseif($rank == 22):
$prom = 1200;
elseif($rank == 23):
$prom = 1400;
elseif($rank == 24):
$prom = 0;
endif;
return $rank;
}
?>