This is my formula but what I should be getting for: B's, C's & D's is not
what I am getting:

=LOOKUP(D18,{"a","a-","b+","b","b-","c+","c","c-","d+","d","d-","f";4,3.7,3.3,3,2.7,2.3,2,1.7,1.3,1,0.7,0})* E18

As you can see from my spread sheet I am getting the wrongs numbers:

A 1 4
A- 1 3.7
B+ 1 3.3
B 1 3.7 (should be 3)
B- 1 3.7
C+ 1 2.3
C 1 2.7 (should be 2)
C- 1 2.7
D+ 1 1.3
D 1 1.7 (should be 1)
D- 1 1.7
F 1 0

Can someone please tell me where my formula is going wrong. Because for the
rest of the sheet there should be nothing showing if there is no grade to
enter.