By default, Plesk sets PHP to "safemode" during installation. To take PHP out of "safemode," you need to remote connect to your dedicated server and modify the php.ini file on the server.
To Turn off PHP "safemode" in Windows
safe_mode = on to safe_mode = off. Once you have edited the file, you need to restart your Web server. You can restart your Web server using Plesk by selecting stop/start under the Server> Service Management section.