index-match function across different worksheets
 

Hi guys,

I have different worksheets to contain information from different years. To make it comprehensive, I have created a mastersheet which contains all the info across the worksheets. And once I make an entry in the worksheet, I hope the mastersheet can be updated automatically. the formula set is INDEX('2011-12'!K$4:K$7,MATCH(Master!$B5,'2011-12'!$B$4:$B$7,0),1). Yet, my problem is..... once I perform sorting in the mastersheet, the data are wrongly matched. So, I just wonder how I can revise the formula? Many thanks!