hyperlinks not working

Hi,

I created a spreadsheet (Microsoft Office Excel 2007) with some hyperlinks in the first tab that link the following tabs (like ta TOC), and then the following tabs link back to the first tab.
The problem is that when I save it as a .pdf document (File > Save as > Adobe PDF) the hyperlinks do not remain as such in the pdf document.
I'm using Adobe Acrobat 9 Pro trial version.

Am I missing something?

Thanks in advance for your comments,

Laura