Why in create security?

Fatal error: Uncaught Error: Call to a member function SetTag() on null in C:\Program Files\NetMake\v9-php81\wwwroot\scriptcase\devel\class\page\nmPageSecurityModule2.class.php:959 Stack trace: #0 C:\Program Files\NetMake\v9-php81\wwwroot\scriptcase\devel\class\page\nmPageSecurityModule2.class.php(544): nmPageSecurityModule2->doReplace() #1 C:\Program Files\NetMake\v9-php81\wwwroot\scriptcase\devel\class\page\nmPageSecurityModule2.class.php(113): nmPageSecurityModule2->generate_step(‘2’) #2 C:\Program Files\NetMake\v9-php81\wwwroot\scriptcase\devel\class\page\nmPageSecurityModule2.class.php(71): nmPageSecurityModule2->CheckAjax() #3 C:\Program Files\NetMake\v9-php81\wwwroot\scriptcase\devel\class\page\nmSite.class.php(95): nmPageSecurityModule2->__construct() #4 C:\Program Files\NetMake\v9-php81\wwwroot\scriptcase\devel\lib\php\base_ini.inc.php(1683): nmSite->Run() #5 C:\Program Files\NetMake\v9-php81\wwwroot\scriptcase\devel\lib\php\base_ini.inc.php(2): sg_load(‘68ABBE04C7C5024…’) #6 C:\Program Files\NetMake\v9-php81\wwwroot\scriptcase\devel\iface\security_module2.php(23): include_once(‘C:\Program File…’) #7 {main} thrown in C:\Program Files\NetMake\v9-php81\wwwroot\scriptcase\devel\class\page\nmPageSecurityModule2.class.php on line 959