In a 3750 running 12.2(40)SE I have configured 2 port-channel groups (po1 and po2) linking to 2 different 6506/6509 switches. What I see is only one port-channel interface (po1) counters is working. Other one is always showing 0 input and 0 output rates although it's passing the traffic. From 6500 switch I can see the port-channel interface counter is increasing. How do I configure the 3750 so both port-channel group interface counters work?