I have this formula entered into a range of cells -
=IF(ISNA(VLOOKUP(B5,April,D$2,FALSE))=TRUE,"",VLOOKUP(B5,April,D$2,FALSE))
This will produce either a number (negative or positive or zero) or a
blank cell. (Is "" a blank cell?)

I have conditionally formatted the range to change the font colour to
white if the value is equal to zero (effectively hiding zero's) and
wish to add an additional condition changing the cell colour to grey if
it is a blank cell (or equal to "").

How do I / Can I do this?

The formula above works, but can it be improved?

My grateful thanks to all who respond.
Dave Moore