How to Calculate a Running Total

Summary

Header Field to total the Line Amounts below

Content

Hello,

I have a page designed (attached) that includes a Header Section and Lines Section.  There can be many lines associated to one Header record.  I would like to obtain the total lines amount (e.g., a running total) and present it in a field on the Header.

The Header is tied to a Business Object while the Lnes are assigned to an ADP.

I've create a function and assigned that to the the Running Total field but it does not work.  The function cycles through the Array and totals the amount.  Here is the function: