Windows 7: Can't enable Wireless WOL on Toshiba Laptop

I am running a new Toshiba Laptop with windows7 over Logmein, which works fine.
I have set the switch off function to "Standby" hoping to be able to wake it up via Logmein if it is switched off.
I have tried to enable the WOWLAN function in the power management of the internal WLAN card of the laptop (Allow this device to wake up the computer ) but the check box is greyed out.
If found the same problem in other forums but without an answer.
There was one similar thread also here but in that case the user had a USB WLAN adapter and this appeared to be the problem.
The technet page Configure Wake on Wireless LAN (WoWLAN) treats the same thing but then a user comments that notwithstanding having done what they say, the box is still greyed out.

So what has to be done?