Difference on P/L when running month to month and over few months

HI all

I have a question.

A client has this issue, when she runs her PL from:

• 01/01/2011 to 31/01/2011, the Profit Period is: R699 012.98
• 01/02/2011 to 28/02/2011, the Profit Period is R 294 664.79

However when you run it from 01/01/2011 to 28/02/2011, the profit period is:

• January 2011: R698 539.26
• February 2011: R294 191.07

They on 2007 and want to upgrade if this issue gets fixed. I tested it on SAP8.82 PL04 and it gives the same scenario...but when i choose life-to-date instead of year-to-date in the balance comparison in the selection criteria...the all the totals are the same whether i run it individual months or from jan - feb..over 2 months.

would that be the correct way to run it, because

• Life to Date – to display the balance from beginning of
  company activity up to the date defined in the From field.
• Year to Date – to display the balance from day one of
  the selected posting period up to the date defined in the From field.

Why would it show different amounts if u select one or the other?

thank you

Jerusha