Share Queue between class?

Hi all,

I am using IUS583. And I want to do transaction layer class object transfer using Queue.
I think there maybe two methods listed below.
1. share queue with two different class
2. share queue (maybe local queue) with two different tasks within one class
My queue contain class object, is it feasible in IUS583? And is there any simple example to do that work?

I have write method 1 and method 2 ,but it seems IUS583 always give out ncelab error:
ncelab: *E,CUVHNF Hierarchical name component lookup failed at 'cmd_queue'.

//method 1 snippet
module top_tb;
class cmd_c;
...
endclass

cmd_c cmd_queue[$];

class transaction_gen;
task run;
    ...
    cmd_queue.push_back (cmd)
endtask
endclass

//method 2 snippet
module top_tb;
class cmd_c;
...
endclass