You don't need IF in CF, as you are only interested in a TRUE/FALSE value.
You can use it, but it is unnecessary.

Change the Condition to Formula Is and use

=OR(A1="",A2="")

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HTH

Bob Phillips

(remove nothere from email address if mailing direct)

"John" wrote in message
...
I have 2 cells which I select entries from a drop-down (A1 and A2) B2 then
does a simple subtraction of whats selected in A1 and A2

A user can select only A1 or A2, this would be incomplete thus I want in
this instance to "blank" out the value returned in B2 i.e. with white
font,
as the result is not very meaning full

How would I do this under conditional formatting in B2

I thought of something like this if(or(A1=" ",A2=" "), but don't think you
can use "IF" in conditional formatting


Thanks