I have used this software lots,
First of all remove all other devices and hardwire straight into the device you want to assign the ip address to,
then set your lan conneciton to dynamic.
Open the software and under options/tools or config not sure what its called, enter in the subnet mask 255.255.255.0 and nothing else
then select browse and wait till you see your mac address...
then select the devices mac address and make sure in shows up in the bottom window
Next there are differences with certain devices....some you can just assign an i.p straight away, others you need to go back to your Lan ip settings then put your network card in the desired range i.e static ip addressing
if you want your device to be 192.168.1.2
subnet 255.255.255.0
your laptop will have to be 192.168.1.xx ''anything other than 2''
255.255.255.0
that should do the trick,
then go back to the boot/p software that is still running and disable the bootp etc
few other notes, the mac address can take a long time to pop up so be patient 5mins and it should be up by then
your device needs to be broadcasting its mac address so make sure thats happenig
also some laptops have firewalls that stop this software from working so dont be afraid to use another pc/laptop