My formula wont calculate automatically in Excel

[Guest]

For some strange reason, I can start a spreadsheet, a very simple one and do
a running total sum - it works.

Then half way through, if I go in and change a value in the same column that
was adding correctly, it ceases to add up automatically. I then have to go
back into the totalling forumla and hit enter to make it register the new
value - any ideas as to why it won't automatically add up?

 

[garfield-n-odie [MVP]]

In Excel, click on Tools | Options | Calculation tab | Automatic
| OK.