Hi,

I got data as follows:
Date Material ($) Labour ($)
1/1/09 100 -
22/1/09 - 150
2/2/09 200 100


and I used formula
=SUMIF('Material (5-1020)'!$A$14:$A$718,"=1/1/ 2008",'Material
(5-1020)'!$H$14:$H$718)-SUMIF('Material (5-1020)'!$A$14:$A$718,"1/31/
2008",'Material (5-1020)'!$H$14:$H$718)

to get the result:
Jan 09 Feb 09 total
Material 100 100 250
Labour 200 100 300

The total amount is linked to other report

The problem is when I open the file together with the report file to get the
link automatically, sometimes I found the result become error like double
duplication result as follows

Jan 09 Feb 09 total
Material 100 100 200
Labour 200 200 400

However the formula does not change at all.

Could anyone help me for this problem?