They may need more coaxing than just lemongrass oil. You should consider opening the box up and helping them pack. There are videos on cut outs but since it is your own hive you won't run the risk of getting sued by yourself if something happens to go wrong. I wish I could help but am super beeez with the Fair.
Where are you? Or, where are the bees? Kevin is correct, you need to do a transfer. They are fun!