Passing a variable by URL – WordPress Rewrite rules

Hello,

I am trying to pass a php variable through the url using WordPress rewrite rules. I am passing the variable from a custom post type archive to a static page with a wp_query for the same custom post type. The neat permalink for the page is ‘/archive-exhibitions’ This is the code in my functions.php template:

//Rewrite rules for URL variable passing

add_filter('rewrite_rules_array','wp_insertMyRewriteRules');
add_filter('query_vars','wp_insertMyRewriteQueryVars');
add_filter('init','flushRules');

// Remember to flush_rules() when adding rules
function flushRules(){
	global $wp_rewrite;
   	$wp_rewrite->flush_rules();
}

// Adding a new rule
function wp_insertMyRewriteRules($rules)
{
	$newrules = array();
	$newrules['archive-exhibitions/([^/]+)/?$'] = 'index.php?pagename=archive-exhibitions&yearlink=$matches[1]';
	$finalrules = $newrules + $rules;
        return $finalrules;
}

// Adding the var so that WP recognizes it
function wp_insertMyRewriteQueryVars($vars)
{
    array_push($vars, 'yearlink');
    return $vars;
}

//Stop wordpress from redirecting
remove_filter('template_redirect', 'redirect_canonical');

?>

I get a 404 error when I try to resolve the link – any suggestions?

My template link to save the variable is:

echo "<li><a href='/archive-exhibitions&yearlink=" . $yearlist . "' >". $yearlist . "</a></li>";

and I am using this to pull the variable onto the static page:

<?php $year = urldecode($wp_query->query_vars['yearlink']); ?>

Any help is much appreciated.

Thanks,

Josh