255 sheets is the limit for a new workbook.

More can be added after the workbook is open if your resources will allow.


Gord Dibben MS Excel MVP

On Wed, 25 Jul 2007 11:04:03 -0700, Stephane Quenson
wrote:

If you have links to external spredsheets, then each of these external
worksheets are considered as one worksheet in your document, even if not
visible. This is how Excel can still display informationif even if the links
are not updated, by the way.

So you may have reached the limit of worksheets per document, which is 255
if I am not mistaken.

Stephane.