this is what you do
And it's going to be more about training you than training the dog
Best if you are not sitting on the floor with this because if the treat you are using is more up in the air they are less likely to lie down when you give the command
Also AS you give the command ... Hold e treat in your fingers and
Turn your hand UP with your wrist
This way the dog will need to keep his head up to get the treat
Keep practicing that move
And you get the trick sooner or later.