If you call a object method with call_user_method(), it can't handle its own object properties anymore. The demo below returns 1,2,3 for the direct calls as expected, but then just 4,4,4 for the indirect calls.    

class test
    {
        var $a=0;

        function increase()
        {
            $this->a++;
            echo "a is now: ".$this->a."\n<br>";
        }

    }


    $t = new test();

    echo "Direct calls:\n<br>";
    $t->increase();
    $t->increase();
    $t->increase();

    echo "<p>\n\nIndirect calls:\n<br>";

    call_user_method ("increase", $t);
    call_user_method ("increase", $t);
    call_user_method ("increase", $t);