I'm working with an Excel workbook I prepared with Excel 97 or 2003.  I resaved it in 2007 format but cannot get the worksheet/workbook protection to work - the Protect Worksheet and Protect Workbook icons appear to be inactive (greyscale).  I have 5 sheets which are all interconnected and I haven't worked with it for 2 years. I keep writing over formulas - need to pay more attention.

Does anyone have suggestions on what I may be doing wrong.

TIA