Fatal error: Class 'Tools' not found when install

[leestars]

When I want to install prestashop V1.7. It show:

 

Fatal error: Class 'Tools' not found in /home/wwwroot/www.testtest.com/config/config.inc.php on line 52

 

and if i just open install url. It show:

 

Fatal error: Class 'Tools' not found in /home/wwwroot/www.testtest.com/testtestnew/config/defines_uri.inc.php on line 68

 

And I have check the classes/Tools.php is exist. 

 

on the config.inc.php on line 52: code is as below:

Tools::redirectToInstall();

 

 

 

on the defines_uri.inc.php on line 68: code is as below:

Tools::safeDefine('_PS_API_DOMAIN_', 'api.prestashop.com');

 

Why Class Tools can't work right?

I also try to set chmod 777 to all files. But it still don't work OK. 

 

Is there any matter with the php version? Please someone help me. Thanks!

[leestars]

My php version is PHP Version 5.6.30