Cisco busyout problem

Hi Guys,
I’m running a cisco 2610 with a T1 controller in it and connected to the analog lines via ch bank and configured with e&m immediate-start signalling and g.729r8 codec. I had to make some channels busyout and it’s ok. But if cisco unit or the ch bank get a reset and sometimes while no reset is performed, those ch get back to on-hook state that supposed to be busyout. Still busyout configuration line is there in the config file.
Can anyone explain why it happens and how to fix?
Thanx