Couple of reasons:

- Custom formats can only have 3 numeric format fields, not 4.

- your [Blue] format doesn't have a numeric format.

- if you have numeric ranges in your custom format, the ranges must
encompass all numbers. In your format string, the format of any value
<0.01 is undefined.

- the syntax for greater than or equal to is "=" rather than "="

See

http://www.mcgimpsey.com/excel/conditional6.html


In article ,
bob sacco wrote:

I'm attempting to color code a series of numbers using the custom number
format in the FORMAT MENU.

I need to color code four numbers (or ranges of numbers)

10%, 50%, 90% and 100%

Currently I have:
[Yellow][=0.01] 0%;[Green][=0.05]0%;[Blue][=0.09];[Red][=1]0%;@

But I can't get it to work.

Any ideas why?