Creating a module that depends on themekey, help with API

Documentation is not that good in this module. I have followed the few example files and I have developed some code that is not working as expected. Let's see if someone can help me.

I am developing a submodule of moneysuite affiliates suite (https://www.drupal.org/project/moneysuite) so that a webmaster can develop, let's say, a white label theme, and show this theme to users that come from some affiliate.

I have developed three files following the guide of themekey example. The idea is that a themekey rule can be constructed depending on the value of affiliateID of a user.

ms_affiliates_themekey.module

<?php

/**
 * @file
 *   ThemeKey support for changing theme depending on affiliate,
 *   good for white label templating while maintaining original
 *   theme on website for non affiliate visitors
 */

/**
 * Implementation of hook_themekey_properties()
 *
 * Two assign a value to a property during a page request
 * you have three possibilities:
 * 1. Provide a mapping function from one property
 *    to another and tell ThemeKey about it using this hook.
 * 2. Implement hook_themekey_global().
 * 3. Implement hook_themekey_paths().
 *
 * There's an example implementation of this hook,
 * @see themekey_example_themekey_properties()
 *
 * @return
 *   An array of ThemeKey properties and mapping functions:
 *     array of ThemeKey property attributes:
 *       key:   namespace:property
 *       value: array(
 *                description => Readable name of property (required)
 *                validator   => Callback function to validate a rule starting with that property (optional)
 *                               TODO: describe validator arguments and return value
 *                file        => File that provides the validator function (optional)
 *                path        => Alternative path relative to dupal's doc root to load the file (optional)
 *                static      => true/false, static properties don't occur in properties drop down
 *                               and have fixed operator and value (optional)
 *                page cache  => Level of page caching support:
 *                               - THEMEKEY_PAGECACHE_SUPPORTED
 *                               - THEMEKEY_PAGECACHE_UNSUPPORTED
 *                               - THEMEKEY_PAGECACHE_TIMEBASED
 *                               Default is THEMEKEY_PAGECACHE_UNSUPPORTED (optional)
 *              )
 *     array of mapping functions
 *       key:    none (indexed)
 *       value: array(
 *                src       => Source property path (required)
 *                dst       => Destination property path (required)
 *                callback  => Mapping callback (required)
 *                file      => File that provides the callback function (optional)
 *                path      => Alternative path relative to dupal's doc root to load the file (optional)
 *              )
 */
function ms_affiliates_themekey_themekey_properties() {
  // Attributes of properties
  $attributes = array();

  $attributes['ms_affiliates:affiliate_id'] = array(
    'description' => t('The affiliate id a user came from'),
    'validator' => 'ms_affiliates_themekey_validator_aid',
    'file' => 'ms_affiliates_themekey_validators.inc',
    'page cache' => THEMEKEY_PAGECACHE_SUPPORTED,
  );

  // Mapping functions
  $maps = array();

  $maps[] = array(
    'src' => 'system:dummy',
    'dst' => 'ms_affiliates:affiliate_id',
    'callback' => 'ms_affiliates_themekey_map_aid',
    'file' => 'ms_affiliates_themekey_mappers.inc',
  );
  return array('attributes' => $attributes, 'maps' => $maps);
}

ms_affiliates_themekey_validators.inc

<?php

/**
 * @file
 * Validator functions for the Affiliates Suite Themekey module.
 */

/*
 * name: ms_affiliates_themekey_validator_aid
 * Validates a Theme Switching Rule that depends on the affiliate ID of Moneysuite Affiliates Suite.
 * Allowed Operators: "=", "!"
 * Allowed values: string of digits (numbers)
 *
 *
 * @param $rule
 *   A Theme Switching Rule as associative array:
 *   - property: ThemeKey property as string (e.g., "drupal:path")
 *   - wildcard: optional string, only used if property is "drupal:path:wildcard"
 *   - operator: ThemeKey operator as string ("=", "!", "<". "<=", ">", ">=", "~")
 *   - value: ThemeKey property value as string
 *
 * @return
 *   An associative array of errors:
 *   - property: translated error message as string
 *     describing a problem with the property
 *   - wildcard: translated error message as string
 *     describing a problem with the wildcard
 *   - operator: translated error message as string
 *     describing a problem with the operator
 *   - value: translated error message as string
 *     describing a problem with the value
 *   If no errors detected the array is empty.
 * 
 */
function ms_affiliates_themekey_validator_aid($rule){
	$errors = array();
	
	switch ($rule['operator']) {
		case '*':
		case '!*':
		case '<':
		case '<=':
		case '>':
		case '>=':
		case '~':
		case '!~':
			$errors['operator'] = t('Possible operators are "=", "!"');
			break;
		case '=':
			if ('0' === $rule['value']) {
				$errors['value'] = t('Use a value different from "0" to compare to an affiliate id');
			}
			elseif (!ctype_digit($rule['value'])) {
				$errors['value'] = t('Affiliate id value must be a number');
			}
			break;
		case '!':
			if ('0' !== $rule['value']) {
				$errors['value'] = t('Use value "0" to identify all users with affiliation');
			}
			break;
		default:
			$errors['property']=t('Unknown error');
	}
	return $errors;
}

ms_affiliates_themekey_mappers.inc

<?php

/**
 * @file
 * Mapping functions for the Affiliates Suite Themekey module.
 */

/*
 * 
 * name: ms_affiliates_themekey_map_aid
 * 
 * ThemeKey mapping function to set a
 * ThemeKey property's value (destination)
 * with the aid of another ThemeKey property (source).
 *
 * src: system:dummy
 * dst: ms_affiliates:affiliate_id
 *
 * @param $data
 *   string containing current value of ThemeKey property user:aid
 *
 * @return
 *   user affiliate id from Moneysuite Affilates Suite for current user
 */
function ms_affiliates_themekey_map_aid($dummy){
	global $user;
        watchdog('ms_affiliates_themekey','Affiliate detected with UID='.$user->uid.', and affiliate id='.ms_affiliates_get_affiliate($user->uid).' changing theme');
	return ms_affiliates_get_affiliate($user->uid);
}

My problem is that watchdog doesn't show the message line in mappers function and theme is not being switched. Any help on how to proceed?