If you need to deal with a tabular form created by the wizard, you will need to use a slightly different approach. I discussed that topic yesterday evening with Patrick Wolf. The difference to the first approach you can find here:
The full explanation and the code are there as well. Basically, what you need to change is the way you get the rownum. Using $x(this).id will give you the current item id. Substr(4) will give you the last four digits of it (thanks Patrick) and putting that four digits in the Number() function gives you the row number (ROWNUM). You could use that value to loop through the table and update other values, not corresponding to that particular row.