My three chicks are about 7 weeks old and are having trouble understanding the use of the ramp/ladder. Their door is about 4 feet up from the ground, so it is a longish ladder. Yesterday they just came out the door and then flew down to the ground, but today I left the door open all day long and they never left the coop once. I thought for sure they could be lured out with grapes, but no deal. Is there a trick to this I don't know?