hi - I can't seem to get this working.

I have data that looks like:

Salesrep  budget_period1   budget_period2  budget_period3
100                5000                     5500                     6000
110                8000                     8030                     7500
...and so on.

For a selected salesrep, I need to produce a line chart graphing the budget for each period, so that the periods are across the bottom axis. My problem is that I need to have a date field to use for the "on change of" field for the chart (otherwise I just get distinct points on the chart, and no lines)

I thought I could do something like this:

create a group for each of the budgets and in each group place a  counter formula that increments for each group - so that group 1 is for budget_period1 and the formula returns "1', group 2 is for budget_period2 and the formula returns 2, etc.

But my counter formula uses "while printing records" and then I can't use this in the chart.

Am I making this more complicated than it needs to be? Is there some other way to do this?