Two possible issues: 1) do the chicks know how to use the ramp, have you seen them going up and down it? 2) is there any lighting inside the coop portion or windows sufficient to let in ample natural light?  Chickens cannot see in the dark and will not want to go inside a dark box.
I'm actually a big believer in locking them in the coop for a few days as that helps home the chickens without much further effort but that's not possible with most prefabs as there simply isn't enough space inside.
	
		
			
		
		
	
				
			I'm actually a big believer in locking them in the coop for a few days as that helps home the chickens without much further effort but that's not possible with most prefabs as there simply isn't enough space inside.
 
	 
 
		 
			
		
		
		
	
	
			
		 
			
		
		
		
	
	
			
		 
			
		
		
		
	
	
			
		 
 
		
 
 
		 
 
		
 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		 
 
		