Multidimensional Array - IP.Nexus (IPB)

This seems to be highly illogical, but I'm working on a web-shop and I'm trying to grab a package/item display name using the IP.Nexus API (not important).

This is part of the array returned by the invoice script:

invoice Object
(
[data:invoice:private] => Array
    (
        [i_status] => pend
        [i_title] => BETA Tag, ALPHA Tag
        [i_member] => 1
        [i_items] => Array
            (
                [0] => Array
                    (
                        [act] => new
                        [app] => nexus
                        [type] => product
                        [cost] => 0
                        [tax] => 0
                        [renew_term] => 0
                        [renew_units] => 
                        [renew_cost] => 0
                        [quantity] => 1
                        [physical] => 
                        [shipping] => Array
                            (
                            )

                        [subscription] => 
                        [weight] => 0
                        [itemName] => BETA Tag

Surely, to grab itemName, I would use,

$invoice['i_items'][0]['itemName']

Though for some strange reason, that isn't working. Am I missing something?

Based on your information, you are trying to access a private data member. You need to use the public interface for the class invoice.