It doesn't matter if the number of sheets vary. Just use two dummy
sheets, say SheetFirst and SheetLast. Put all other other sheets in
between these two. Your formula should be
=SUM(SheetFirst:SheetLast!C28)

--
Regards,

Tushar Mehta, MS MVP -- Excel
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

In article ,
says...
The number of worksheets will vary from workbook to
workbook.

As for "macros", perhaps I mis-use the term, but I can run
the functions from the "macro" dialog, if I desire...

Rich
-----Original Message-----
Why are you using a macro for anything?

Assuming that the individual sheets have their total in
cell C28, on
the summary worksheet, use =SUM(Sheet1:Sheet10!C28)

where Sheet1 and Sheet10 are the first and last
worksheets of interest
to you.

--
Regards,

Tushar Mehta, MS MVP -- Excel