Just some thoughts ..

> The formula above works, but can it be improved?

The "=TRUE" part is not necessary, so the formula could be just:
=IF(ISNA(VLOOKUP(B5,April,D$3,FALSE)),"",VLOOKUP(B5,April,D$3,FALSE))

> I have conditionally formatted the range to change the font colour to
> white if the value is equal to zero (effectively hiding zero's) ..

As a simpler? alternative, to hide/suppress all zeros display in the sheet,
we could just make the setting:
Tools > Options > View tab > Uncheck "Zero values" > OK

> ... condition changing the cell colour to grey if
> it is a blank cell (or equal to "") ...

Assuming the range of cells is C5:C10 (formula above copied down from C5)
just select the range (C5 will be active), and then conditionally format
with the formula: =C5="" in the desired gray fill. The CF formulas for each
cell in the range will auto-adjust relatively to suit.
--
Rgds
Max
xl 97
---
GMT+8, 1° 22' N 103° 45' E
xdemechanik <at>yahoo<dot>com
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"DaveMoore" <david.moore@uuplc.co.uk> wrote in message
news:1119511598.389893.181620@g49g2000cwa.googlegroups.com...
> 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
>