Channel groups are automatically defined. In current switches they are in groups of 4 ports across the ports of a single module. You only need to define them if you want to split the group across cards like you did. The ports in each group can become a part of a channel but they are not in a channel unless they show up in sho channel. When you do a show channel group you should see a display that shows how channels can be formed, not that they are formed. The only way I can think that may remove them from a group is to set the ports to channel mode off.
