Cannot refer to 'error' = #N/A cell output

I have a formula set up such that it will use a dual condition INDEX & MATCH command and when result cannot be found, the cell value returns #N/A.

I'm trying to use Conditional Formatting to flag the cell (highlight as red) when it returns this 'error' value but unable to do so.

Possible cell values are:

* 0
* text (if it exists)
* #/N/A

I have set up Conditional Formatting such that the out output of 0 is set as white ~ invisible.

Any ideas? I'm stumped.....

P.S. Trying to avoid Macro (if possible)

When doing your CF use the formula =ISNA(cell address) and select the red fill as the format.

It does not seem to work - maybe my example.xls can explain it more clearly.

It should. Please see the attached.

Sorry my bad - Forgot to set it as "FORMULA IS" - now I get it. I was using equal to before. Thanks guys! =D