Question pm_Settings::set always report missing class

[qtwrk]

Hi,

I need to run

pm_Settings::set('some-thing-here', 'some-value-here')

so I wrote a php , and run it by "plesk php php.php" , the problem now I have is

It keeps return Class no found

PHP Fatal error: Class 'DomainService' not found in /usr/local/psa/admin/plib/AbstractDSMail.php on line 3
exit status 255

I even tried blindly include all files /usr/local/psa/admin/plib , still having that issue.

any help would be much appreciated.