Counting length in portal records

[Patricio Mason]

In a calculation, I'm using the Length function to keep track of the 
number of characters in a field. But the field is in a portal, set to 
show three rows, and the calculation it only works for the first row.

How do I make it count the length of contents in each individual row?
TIA.

Saludos,

Patricio Mason
Santiago, Chile
www.ics.cl