Problem with WPML multilangual

Hi, same error than previous user…

Fatal error: Uncaught Error: Call to a member function using_permalinks() on null in /wp-content/plugins/html-after-url/html-after-url.php:46 Stack trace: #0 /wp-includes/class-wp-hook.php(303): amm_hau_remove_slash(‘/ru/’, ”) #1 /wp-includes/plugin.php(189): WP_Hook->apply_filters(‘/ru/’, Array) #2 /wp-content/plugins/sitepress-multilingual-cms/classes/utilities/class-wpml-slash-management.php(82): apply_filters(‘user_trailingsl…’, ‘/ru/’, ”) #3 /wp-content/plugins/sitepress-multilingual-cms/classes/utilities/class-wpml-slash-management.php(52): WPML_Slash_Management->user_trailingslashit(‘/ru/’) #4 /wp-content/plugins/sitepress-multilingual-cms/classes/url-handling/converter/strategy/class-wpml-url-converter-subdir-strategy.php(113): WPML_Slash_Manage in /wp-content/plugins/html-after-url/html-after-url.php on line 46

How can I solve? I’ve tried to put the code suggested by Sergiy in my Child theme Functions.php… but nothing has changed.

Thanks in advance