In Excel blank cells have a numeric value of zero, so your formula will not work for CF.

If you want Cf to highlight non-blank cells in the range, you could something like LEN(A1)>0.

You suggest at the start of your thread that you are matching cells. Possibly you could create a CF formula to look at whether or not a matching value is found.

Upload your workbook or provide more details if the above is not what you need.