丢失数据调用php中的几个方法 - OOP

Perhaps it is a very simple issue, but I'm missing something in OOP fundamentals. Suppose I have to php file, say file1 and file2. file1 implements a class from the class Class, and in some of the method of the latter, say MethodA. In MethodA, I instantiate a class say $object from the class Object (which comes from another file3), and I call a method, say MethodB that takes as an argument the instantiation $object, and processes to set the value of one attribute of the instantiation $object. So, the scheme is the following :

class Class{

    public function MethodB($object){

        $param
        ...
        $object->setValue($param);
        ...

    }

    public function MethodA(){

        $object = new Object;
        ...
        $this->MethodB($object);
        ...
        $object->getValue();
    }

}

Now the problem is that I am not able to get back the value of $object->getValue($param), and the question is why?