If / Then fomula : I want a formula that answers if x <= y then "a" but if x <= z then "b" but if > z then "0"

I've tried several things, this is the closest I've come to solving.  
=IF(A36>8,0,IF(A36<=8,"1 Case",IF(A36<=4,"2 Cases")))
anything less than 8 always gives me the 1 case answer.  
