I speak a litle English (very good Italian)

George         01/01/2004 (selection from list)       31/12/200
(selection from list)      
Gregory        23/06/2004 (selection from list)      30/12/2004
(selection from list)      
Peter             01/04/2004 (selection from list)      20/05/2004
(selection from list)      
etc

I have many workers about 150 persons. One of them works from dat
01/01/2004 to 31/12/2004. No continually in the year. For examble fro
03/01/04 to 15/02/04 and 10/03/04 to 10/04/04 etc.
If he works in the first period from 03/01/04 to 15/02/04 he take 50,0
? every day,
If he works in the second period from 10/03/04 to 10/04/04 he tak
70,00 ? every day, etc.

My problem is:
for examble,
I select the period 03/01/04 to 15/02/04 when the worker take 50,00
every day
If I select the period 10/02/04 (and non 10/03/04) to 10/04/04. Thi
mean I make a wrong selection.
I want from excel to say me ?wrong selection? or ?wrong selection? fo
any wrong selection and for any worker.
What I have to d