How can I calculate the sum of the first two rows in a table?

I have a table with a repeating row that, when data is merged, always has three rows:

I have a field where I want to show the sum of Support types 1 and 2.

I do not want to add the interest to this.

I'm using FormCalc with the following script on the calculate event of the Total field, which is in the same subform but not in the table:

data.JP_Page1.subform_Hidden.sub_SupportTotals.NumericField1::calculat e - (FormCalc, client)

$.rawValue = Sum(subform_Hidden.sub_SupportTotals.tbl_SupportSubtotals.DataRow[0]. SUBTOTAL,  subform_Hidden.sub_SupportTotals.tbl_SupportSubtotals.DataRow[1].SUBT OTAL)

I've tried this using both decimal and numeric field types, neither work.

I feel like I must be hitting a syntax issue, but the code checker isn't exposing it.

Can anyone help me figure out what is wrong with my script?

Thanks!

Janet