My workbook is built dynamically... I have N number of sheets and ONE summary sheet where I want to calculate the sum (for the same cells address) of the others. By example...

If I have this...
Sheet 1 - Range("A1") = 500
Sheet 2 - Range("A1") = 400

I want SumSheets() function return 900...
Summary Sheet - Range("A1") = SumSheets(ligne();colonne())

That works. But my problem is the value is not refreshed after I change something in the Sheet 1 or Sheet 2. I tried to place a calculate method in activate event of the summary sheet, but nothing change. Why the call of the function is not trigger? And is it a better way to do what I need?
Thank you!