Formula problem when trying to arrive at a total

[verifier]

All:

I am having trouble coming up with the proper formula on the attached Excel sheet. Here is what I am trying to do:

I need the Delivered Correctly total in cell I-16 to include the information already in the cell plus the totals from cells I-19, I-20 and I-21. The Delivered Correctly total must include the Pileup (Not Delivered), For Sale (Delivered) and For Sale (Not Delivered). No matter what I try, I receive an error message informing me my formula is incorrect.....I am at a loss.

Any assistance would be greatly appreciated.