add_rewrite_rule() not working

I need to pass a property reference the last part of a URL to search the database for an entry, eg,

http://ift.tt/1Cd2QGU

I need to pass the G638 into an array for my plugin. What I have below is calling the cottage-details page, but removing the last part of the URL and showing an empty page, rather than the information I wish to retrieve from the server. If I use

http://ift.tt/1Cd2QGW

it works perfectly.

/**
 * Rewrite tags for plugin
 */
function dcc_rewrite_tags() {
    add_rewrite_tag('%propref%', '([^&]+)');
}

add_action('init', 'dcc_rewrite_tags', 10, 0);

/**
 * Rewrite rules for plugin 
 */
function dcc_rewrite_rules() {
    add_rewrite_rule('^[^/]*/([^/]*)/?','index.php?p=2&propref=$matches[1]','top');
}

add_action('init', 'dcc_rewrite_rules', 10, 0);

What’s going on?