fix a bad bug. lang var ViMod, replaced by VisibilityChanged (trad4all)

main/document/document.php

@@ -604,7 +604,7 @@ if ($is_allowed_to_edit || $group_member_with_upload_rights) { // TEACHER ONLY
 
 		// Update item_property to change visibility
 		if (api_item_property_update($_course, TOOL_DOCUMENT, $update_id, $visibility_command, $_user['user_id'], null, null, null, null, $current_session_id)) {
-			Display::display_confirmation_message(get_lang('ViMod'));
+			Display::display_confirmation_message(get_lang('VisibilityChanged'));//don't use ViMod because firt is load ViMdod (Gradebook). VisibilityChanged (trad4all)
 		} else {
 			Display::display_error_message(get_lang('ViModProb'));
 		}