Sum of formulas (within subform)

Sum of formulas (within subform)

Hi, 

I have a timesheet subform, with an "Hours worked" field, an "Overtime" field and a "Total" formula field that combines the two values.

In the main form, I want to include a grand total field that would be the sum of the "Total" formula for each row.

I've achieved this with "Hours worked" only, but not the sum of "Hours worked" and "Overtime".
  1. input.Total_Amount = input.Total_Amount + row.Hours_Worked;
That works. (in Main Form>Subform>Hours_Worked>On User Input)

  1. input.Total_Amount = input.Total_Amount + row.Total;
That does not. (in Main Form>Subform>Total>On User Input)

Should I be able to sum formula fields like I can sum decimal fields?

Much appreciated!
Levi