Vexing problem, can anyone help please?

Hello and thank you in advance,

The problem I'm having is that the formula is correct and works (thanks to click and drag), but not all rows return the answer even though there is data in the source table. The only thing that changes between rows is the row # (this is intended). I have 80 rows on this sample, but will have a couple hundred, so any help would be greatly appreciated.

Sample screenshot, and I have included a sample file. Thanks again for any assistance!