stuck calculating combined area of circles

Hi All,

I'm having trouble calculation the combines area of a large number of circles in side a surface.

If I do a manual example of a small plane with 6 circles I get the expected/correct result when I combine the areas off all 6 circles and use them as operands to calculate open area, see example: 

...when I apply the definition to an array or circles (in this example 5439 circles) the Mass Addition component is failing to give me a single result for the combined area of all the circles:

what am I missing? any help would be greatly appreciated.

Gustavo