You´re quite right so maybe I didn´t described it quite well :-)
What I mean is that on the 28th of februray, when I "say" [Reporting] -> [Accounting] -> [Select report:] "ThisMonth" I did NOT see the accounting of february but NOTHING. Today, 1st of march, I have the option to look into "2003-02-FullMonth" and everything is fine again... but yesterday it wasn´t...
So, never mind... I was just wondering... this is no big issue to investigate further... :-)