Cacti settings error after install plugin

Error status:
Click Settings in Cacti Console and show error "HTTP 500 Internal Server Error".

Solution:
1. enable php debug.
2. click settings again. The error message is bellow.
"Fatal error: Call to undefined function define_syslog_variables() in C:\Inetpub\wwwroot\cacti\plugins\thold\includes\settings.php on line 132".
3. Google search "Cacti define_syslog_variables()" and find Cacti bug with define_syslog_variables()
4. modify several .php to disable function define_syslog_variables().