is_singular and CPT

Hello,

I try to check if the single page is a Custom Post Type “locahero_profile”.
I created the CPT with the plugin.

When I try to change the author_link on this special CPT nothing happens.

function my_author_link( $link ) {	
	if ( is_singular( 'localhero_profile' ) ) {
		global $post;
			$profile_ID = get_user_meta($post->ID, '_cptID', true);
			$link = get_permalink( $profile_ID );
		return $link;
	} else {	
		return 'HELLO';	
	}
}
add_filter( 'author_link', 'my_author_link', 10, 1 );

Any suggestion why the CPT is not checked? Did I miss some settings?

Cheers,
Denis