can't enable postgrey at boot

Hi everyone,

recently i disabled greylisting then when i reenabled it, i got this message:
Greylisting is not currently fully enabled on your system. Click this button to have Virtualmin configure it.
So i clicked:

Enabling Postgrey at boot time …
… enabled

Starting Postgrey server …
… started OK

Configuring Postfix to use Postgrey …
… already configured

and when i back the message appear again. so i clicked again and then the message appear again Oo

So i’ve been to “bootup and shutdown” section and i discovered that postgrey whas disabled at boot. So i check the box, click on “start at boot” and when i back on the list … surprise … nothing changed!
Postgrey stille marked as disabled at boot!

It seem’s virtualmin doesn’t not recognize the “enabling at boot” status for postgrey

How can i fix it?