Set Custom Formulas for your conditions.

Orange Condition:
=OR(F2="",F2<=3)

Blue Condition:
=AND(F2=4,F2<=20)

Green Condition:
=F2=21

Note that the conditions as you described will not yield formatting for
values between 3 and 4, and between 20 and 21. Thus 3.3 and 20.7 will not be
formatted.

HTH,
Elkar


"Jeff" wrote:

I have a problem with getting conditional formatting to work properly for
me.


What I want to do is use the cell background colour to indicate the number
of items in the cells (column)
I've spent hours trying to get it right :- (

If F2 is equal to or less than 3 (or cell is empty) 'to orange
If F2 is between 4 and 20 'to blue
If F2 is equal to or greater than 21 'to green

Solution gratefully accepted

Jeff