我的OOP PHP方法没有执行

I have file 'class_reg.php' that contains class 'Reg', and some methon 'registration' in it, it recive some input value and insert it into the database via PDO. And I have 'dbconfig.php' file, where I connect to database, include my 'class_reg.php' file and create object '$user'. And I have some 'registration.php' file where I include 'dbconfig.php' file and try to run my method 'registration' but it not work. So here my files:I have file 'class_reg.php' that contains class