site maintenance - how i can?

[platinum]

i use Getsimple 3.0

i tried to use this plugin
Maintenance
http://get-simple.info/extend/plugin/maintenance/29/

but doesn't work (if i choose to enable "site maintenance" by check-box in admin panel, when i save new option the check-box comes back again empty)

is there another solution for a "site maintenance"?

You can always make a backup of the root "index.php". Then just create a new index.php with whatever the maintenance message should say. Then were the maintenance is complete, replace the old file

yes.i tought this solution ....but then all other pages are avaible?!?!?