Why are my functions not executing?

[Charlie]

I spent all this time building a workbook, and now when I enter new data,
none of the calculations happen. If I click on the individual cell with the
function in it and then hit enter, then it works. What's going on?

 

[Elkar]

Make sure Calculations are set to Automatic.

In Excel 2003:
Goto TOOLS-->OPTIONS-->CALCULATIONS-->Check "Automatic"

In Excel 2007:
Goto the Formulas Tab, then click on the Calculation Options button. Check
Automatic.

HTH
Elkar