Validating Dates Entered

How can I set this up?

If Column A is blank then no date can be added to Column B;

If there is a date in Column A then Column B must be equal to or greater (=>) than Column A

Seems like it should be easy enough but I can't get it to work.

Thanks!

One way:

Data/Validation/ Allow Custom:

=AND(A1<>"",B1>=A1)

uncheck the Ignore blank checkbox.

In article <[email protected]>,
patam <[email protected]> wrote:

> How can I set this up?
>
> If Column A is blank then no date can be added to Column B;
>
> If there is a date in Column A then Column B must be equal to or
> greater (=>) than Column A
>
> Seems like it should be easy enough but I can't get it to work.
>
> Thanks!