how to write formulas in same worksheet where db queries are loaded

I've attached part of a workbook which queries a database and loads the last 288 rows of data into tables in my workbook.

I'm trying to write some formulas based on the data in those rows, and that formula is placed below these tables.

However when I do write a formula, instead of giving me the answer, it just copies the formula label. (You'll see this in the workbook if you scroll down below row 300). I've placed some graphics there to point out the cells with the problem.

So... how do I "break" the table so that rows beneath it become regular, empty Excel-style cells?

Thanks!

Thanks for catching that. I had copied the formula from another workbook, only vaguely remembering how the formula worked. The range I wanted to get the average of is I275-I290.
The #15 is a variable so that I can change the average period if needed.

So it averages "up" from 290 rather than down from I3. Row 290 always represents the most recent data.

I think I can fix it now. Thanks for your help!