Data from multiple worksheets

[Smorg1966]

I am working with an excel file that contains 30+ worksheets, at the start is a summary sheet. I am looking at a way so that a figure that is present in every worksheet in the same cell to be displayed on the Summary. I could just create a link each time for the 30+ worksheets but is there an easier way. I have tried to drag down the formula
=IF('Wk1'!$G$31>0,'Wk1'!$G$35,0%)
but when it is dragged it just repeats itself and does not change the worksheet name to Wk2 etc. The worksheets are named Wk1 to Wk32.
Can anyone assist and have i given enough info.

Many Thanks

Smorg

[salman_msssb]

I am facing the problem to collect the data from other sheet in workbook of two refrence one is invoice number and second is code in invoice details.

in invoice details all data feed and second is sales to collect data formully to different code