PHP can't unset array element inside object

I've looked at all the questions about unsetting elements and I'm not making any of those mistakes, but the element is still there after I've unset it.

Update: I've incorporated RichardBernards suggestion below but this is still happening:

    foreach($oldObject AS $key1=>$val1)
    {
        if (!empty($val1)) 
        {
            $newObject->$key1 = $val1;
            if (is_array($oldObject->$key1)) 
            {
                foreach ($oldObject->$key1 as $key2 => $val2) 
                {
                    if (empty($val2)) 
                    {
                        print('Found to be empty: unsetting newObject->' . $key1 . '[' . $key2 . ']');
                        unset($newObject->$key1[$key2]);
                        if (array_key_exists($key2, $newObject->$key1)) 
                        {
                            print('The key ' . $key2 . ' still exists. What is going on?');
                        }
                    } 
                }
            }
        }
    }

In this code, the text "The key still exists. What is going on?" is being printed every time.

I have to unset empty elements because I'm making a SOAP call with the object, and SOAP rejects the object if there are any empty strings in it. But why does $newObject->$var[$key] still exist after I've explicitly unset it?

Is it because I'm trying to unset an element of an array inside an object?

Any help would be greatly appreciated.