Incorrect results from calculated field formula

Hi all,

I have attached a spreadsheet with two pivot tables in it. The one I am working on is on the far right starting at cell AP2. I am trying to calculate the density of each plant species in each transect from my data. I have created a calculated field 'Mean Density' and used the formula =1/(Distance*Distance)*10000. I have used the 'value field settings' option to display 'distance as 'Average of Distance' in one column (excluding zero values) as I need the formula to make the calculation based on mean distance.

The second tab shows an example of the result I should be getting for transect ky2 Water Reserve for the species Hakea platysperma in cell F22. As you can see, this is different from what I am getting in the 'edited data' tab in cell AS19. So I'm doing something wrong...... I would really appreciate any assistance / suggestions.

Thanks very much!