Can't find SimpleXMLElement.php when install version 5.1.5

Connecting to database...OK
Checking database...OK
Creating tables....
Warning: include_once(SimpleXMLElement.php): failed to open stream: No such file or directory in /var/www/html/amember/setup/index.php on line 32

Warning: include_once(): Failed opening 'SimpleXMLElement.php' for inclusion (include_path='/var/www/html/amember/library:/var/www/html/amember/application/default/models') in /var/www/html/amember/setup/index.php on line 32

Fatal error: Uncaught Error: Class 'SimpleXMLElement' not found in /var/www/html/amember/library/Am/DbSync.php:816 Stack trace: #0 /var/www/html/amember/library/Am/Setup.php(205): Am_DbSync->parseXml('<?xml version="...') #1 /var/www/html/amember/library/Am/Setup.php(71): Am_Setup->createTables() #2 /var/www/html/amember/setup/index.php(643): Am_Setup->process() #3 /var/www/html/amember/setup/index.php(756): SetupController->step4() #4 /var/www/html/amember/setup/index.php(844): SetupController->run() #5 {main} thrown in /var/www/html/amember/library/Am/DbSync.php on line 816

fixed by install php-xml and php-simplexml