[ACPI] S3 and S4: nothing happens

[Roy <ro...@we...>]

Anyone can help me with this:
If I do a "echo 3 > /proc/acpi/sleep" or a "echo 4 > /proc/acpi/sleep" 
nothing happens (using 2.5.41 and 2.4.20-pre8-acpi). There isn't any 
message in /var/log/messages.

A "cat /proc/acpi/sleep" gives me: S0 S3 S4 S5

Any suggestions?
Thanks, Roy!