Any statically assigned device should live outside of the dhcp range....When a device connects all you need to do is go to the leases table, click the plus symbol to add a static lease, all you need to do is enter the IP address you want the device to have, and that address MUST be outside the dhcp range you have set. Its a limitation of the server.
As I said just enter the IP address you want to assign to the mac address. Everything else will default to what's in your dhcp settings. If you click on the help icons they say they will use the defaults.