seeing error in custom formula

Content

Hi...I'm creating a report where one of my  data columns has an account that is dynamic calc (sales per sq ft).  Then I have a total line that sums the values from above.  The sales per sq ft account is also summing, which doesn't make sense, so I created a custom formula in the cell for the total to manually calculate divide sales/sq ft.  I also have this line grouped by one of the dimensions in the row (brand).  The first brand, the calc works fine.  But the second brand it errors out and the last brand is calculated incorrectly.