Alert box IF false

[Jacob Walton]

I need an alert box to display if one cell in my worksheet does not
equal another. Basically whenever one thing is added to the sheet,
something else must be added too, but people keep forgetting to add
the second item. I have a sum of each of the two items which, if used
correctly, will always equal the same number. If they do not then
someone has failed to enter the second item and an alert box must be
displayed. Can anyone advise as to how I can achieve this?

Many thanks.

Jacob Walton.

 

[CarlosAntenna]

I don't know about an alert box, but I've used conditional formatting to
change the color of the cell in similar cases.