Hello my name is Jonathan and i am one of the Engineers here at the Cisco SBSC team. I apologize for the inconvenience with this unit. and the delay on the response.
please let me know the following:
Are you still having this issue? if so one of the requirements for the stack to work properly is that all of the units have to be on the same firmware version and boot code as well, so i would recommend to take a look as the firmware versions and if they are different you can do the upgrade. i hope this helps, if you need further assistance or have any questions you can call us at 1-866-606-1866. thanks and have a great day.