The formulas in the spreadsheet are driven by a VBA Module. For modules to work your Excel needs to have Macros enabled.
If you load the spreadsheet and #NAME appears as the output in the cells it means that Macros are not enabled. See instructions below on how to enable Macros for your version of Excel.
Excel 97 - 2000
First, make sure that you can see the Developer tab.
If there is no Developer tab, click on the Office icon to the top left of the application and choose Excel Options, which is located at the bottom right of the popup.
Now click on Popular at the top left. Check the box titled "Show developer tab in the ribbon".
Now, click on the Developer tab.
Click on Macro Security.
Select "Disable all macros with notification" and press ok.
Close and reopen spreadsheet.
Now you should see a Security Warning appear in the toolbar that reads "Macros have been disabled". Click on the options button.
Select "Enable this content" and press ok.
If you have any more trouble feel free to contact me.