ACPI Wakeup reset during reboot

My PC clock is set to local time and I use the folowing script to setup ACPI Wakeup :

#! /bin/bash
SECS=`date -u --date "$1" +%s`
echo 0 > /sys/class/rtc/rtc0/wakealarm
echo $SECS > /sys/class/rtc/rtc0/wakealarm
cat /proc/driver/rtc

When I use this script, shutdown my PC and wait for the wakeup everything works fine.

But If I manually re-start and stop my PC before date/time alarm my PC don't Wakeup.

alrm_time is not changed, alrm_date is changed to ****-**-** (it seems that my BIOS don't use date for wakeup) and alarm_IRQ is set to no

it's like something reset acpi wakeup at reboot.

For information everything was OK with /proc/acpi/alarm on Gutsy (my PC wakeup everynight at 01:00 without have to setup acpi wakeup date/time at shutdown - no date, only time in BIOS wakeup settings)

> sudo set_acpi.sh "2009-07-21 23:00:00"

rtc_time : 22:06:16
rtc_date : 2009-07-21
alrm_time : 23:00:00
alrm_date : 2009-07-21
alarm_IRQ : yes
alrm_pending : no
24hr : yes
periodic_IRQ : no
update_IRQ : no
HPET_emulated : no
DST_enable : no
periodic_freq : 1024
batt_status : okay

> sudo shutdown -r now

... PC restart .....

> cat /proc/driver/rtc

rtc_time : 22:08:46
rtc_date : 2009-07-21
alrm_time : 23:00:00
alrm_date : ****-**-**
alarm_IRQ : no
alrm_pending : no
24hr : yes
periodic_IRQ : no
update_IRQ : no
HPET_emulated : no
DST_enable : no
periodic_freq : 1024
batt_status : okay

> sudo shutdown -r now

... PC stop and nothing happened at 23:00....

Thanks
Yoann