Disable aggregation options for this field

Hi,
I create a simple math field to calculate GDD from weather data and all works well. But when I aggregate, the box

SELECT THE FIELDS TO USE IN THE FORMULA.

disappears.

Also appears this error:

SQLSTATE[42S22]: Column not found: 1054 Unknown column 'field_views_simple_math_field' in 'field list'

and in the query appear the fiedd: SUM(field_views_simple_math_field) AS "field_views_simple_math_field"

The issue appears only if I choose a SQL math operation (SUM, AVG and so on) associated to the VSMF field. Instead if I choose "Group" no error appears.

That's due to the fact that your VSMF executes math operations on fields after aggregations? In this case is bettter to "disable" aggragations options for this field (similat to gloabal: custom text)

Thanks, Antonio