When opening a 2003 version of an Excel Spreadsheet in Excel 2007 I could reference but not unhide a sheet
To solve the problem I just kept a copy of the spreadsheet with the Hidden Sheet shown and reverted back to this one whenever a change was made.
It would not allow me to save as a Macro Enabled workbook as it contained version 3.0 and 4.0 Macros
I finally solved a method of unprotecting the worksheet structure and displaying the hidden worksheet as follows:-
1. Click on the Review Tab
2. Click on Protect Workbook
3. Untick the Protect Structure and Window
4. Enter the password
5. Now right Click on a visible worksheet at the bottom
6. Click OK
7. Select the hidden worksheet by clicking on it and click show