Hi

I would like some help on how to make historical data - progress mesurement
in the following case:

SHEET ONE - TASKLIST
A B C
ID STATUS STATUS CHANGED
------------------------------------------------
1 New 2006-10-28
2 Working 2006-10-29
3 Working 2006-11-01

SHEET TWO - GRAPH DATA
A B C D
Date New Working Closed
2006-10-28 1 0 0
2006-10-29 1 1 0
2006-10-30 1 1 0
2006-11-01 1 2 0
2006-11-02 #NA #NA #NA ToDay = 2006-11-01

I am using a formula like the one below today:
=IF('Graf Data'!$A3<=TODAY();IF(TaskList!$C$5:$C$317<='Graf
Data'!$A3;SUM(IF(IssueLog!$B$5:$B$317='Graf Data'!B$1;1;0);0);0);NA())

This formula almost does the task, but it has a problem when for example New
above is changed to Working (data i automatical set to current date) all old
(historical) data for col B in GrafData is set to 0 - old data is
overwritten. The Working Col. is updated from 2 to 3 as wanted with hist.
data intact.

Any help on this problem would be much appriciated