Validation problem.

[Petter]

Lets make this very simple. I have two cells. Lets call them A1 and B1. I
want the cells to be blank or contain just "X". Anything else should not be
allowed. This i can solve by making a validation rule.I have solved this just
by makeing a list that just contain "x", so you get a dropdown box with just
x in it.

But both cells cant contain "X". This can i allsow solve by makeing a
validation rule.
Here i just added =A1="" in the validation. And offcourse i can add =B1=""
in the other valiation cell.

The problem is that i cant solve both. Need help with this one. Plz.

I dont want to use buttons..cuz this will apply to over 1000 cells.

 

[Stephen]

Select A1 and B1. Apply this formula in Data Validation:
=(COUNTIF($A$1:$B$1,"="&"X")<2)

 

[Petter]

Thx, but this not solve the problem with the first issue. The user can still
put anything want they into the cell. This should only be restricted to
either blank " " or "x".

 

[Stephen]

My apologies. Try this formula instead:
=AND(OR(A1="",A1="X"),(COUNTIF($A$1:$B$1,"="&"X")<2))
(The first two cell references are meant to be relative.)