Win98 irpSp->Parameters.Power.ShutdownType have bug

I encounter a problem
my driver need to know system is Shutdown or Reboot
but in Win98 first edition I can’t receive “PowerActionShutdownOff” message
when Win98 reboot or shutdown I receive same message “powerActionShutdownReset”
that mean my driver can’t separate “Shutdown” or “restart”

but other OS Win98 SE ,Win ME ,Win2000 , WinXP
no this problem , when Reboot driver receive “powerActionShutdownReset”
when Shutdown driver receive “PowerActionShutdownOff”

my driver code
:

switch (irpSp->MinorFunction){

case IRP_MN_SET_POWER:
if(irpSp->Parameters.Power.ShutdownType==PowerActionShutdownReset)

if(irpSp->Parameters.Power.ShutdownType==PowerActionShutdownOff)