Permalinks, permalinks!

I’m attempting to have my WordPress plugin create its own permalinks and after reading through this guide (https://codex.www.ads-software.com/Custom_Queries#Custom_Archives) I copied and pasted the code almost tit for tat:

// Permalinks

function geotag_queryvars( $qvars ){
	$qvars[] = 'geostate';
	return $qvars;
}

global $wp_query;
if( isset( $wp_query->query_vars['geostate'] )) {
	echo 'Permalinks seem to be working!';
}

function geotags_flush_rewrite_rules() {
	global $wp_rewrite;
	$wp_rewrite->flush_rules();
}

function geotags_add_rewrite_rules( $wp_rewrite ) {
	$new_rules = array(
	'geostate/(.+)$' => 'index.php?geostate=' .
	$wp_rewrite->preg_index(1) );

	$wp_rewrite->rules = $new_rules + $wp_rewrite->rules;
}

add_action('generate_rewrite_rules', 'geotags_add_rewrite_rules');
add_action('init', 'geotags_flush_rewrite_rules');
add_filter('query_vars', 'geotag_queryvars' );

if(isset($_GET['geostate'])){
	echo 'GET var is set.';
}

// End Permalinks

So what should happen is /geostate/test/ should be seen as the same as index.php?geostate=test and hence the if(isset($_GET[‘geostate’])){ part should echo ‘GET var is set.’

Similarly the if( isset( $wp_query->query_vars[‘geostate’] )) { part should activate and echo ‘Permalinks seem to be working!’.

When I browse to /geostate/test nothing happens and $_GET remains empty. I can’t understand what I’m doing wrong or not doing, any ideas?