What is exact make and model of the wireless keyboard?
In Windows when wireless keyboard is conencted open control panel > device manager and expland keyboard. Right-click the wireless keyboard and go to properties then go to Power Management tab and uncheck 'Allow computer to turn off this device to save power' and check (enable) 'Allow this device to wake the computer' and hit OK.
Although the wireless keyboard might power itself down when idle to save power/battery. After you checked the above settings try hitting a key first to wake keyboard up and again and see if it wakes the laptop.
Also, each USB Root Hub and Wireless device have their own power properties in the Device Manager. Check power management properties of all of...