LOOKUP does not always give the correct result - correct number of vectors etc checked

the code for the function should look in column A - and from a list, create a result in column C
it looks like this


it does give a correct result in the majority of occurances - EXCEPT for a result of L5c, L6c and L7c

column A is the independent score I input, it is in this case out of a total of 20.

column B has the following
=LOOKUP(A1, {0,0.299,3,4,5,7,9,10,12,14,15,16,17,18,19,20,21},{"L3i","L3c","L3s","L4i","L4c","L4s","L5i","L5c","L5s","L6i","L6c","L6s","L7i","L7c","L7s","L8s","LEP"})

column C is
=LOOKUP(B1, {"L3i","L3c","L3s","L4i","L4c","L4s","L5i","L5c","L5s","L6i","L6c","L6s","L7i","L7c","L7s","L8i","L8c","L8s","LEP"},{3.165,3.5,3.83,4.165,4.5,4.83,5.165,5.5,5.83,6.165,6.5,6.83,7.165,7.5,7.83,8.165,8.5,8.83,9})