Local OG setting Hook gives error.

Hey,

When I try to add the following hook to my functions.php or rank-math.php I get a PHP error or the websites crashes. Other hooks work perfectly. Could you help me out?

/**
* Allow developers to change the content of specific social meta tags.
*
* The dynamic part of the hook name. $network, is the network slug
* and $og_property, is the property which we are outputting.
*
* @param string $content The content of the property.
*/
add_filter( “rank_math/opengraph/facebook/og_locale”, function( $content ) {
$content = ‘da_DK’;
return $content;>

});

From: https://support.rankmath.com/ticket/how-to-change-meta-propertyoglocale-without-changing-site-language-in-wp/