It suggest NETWORKDAYS is referencing data in a worksheet other than the one
in which you have the CF.

You can get round this by using named ranges and referencing these in you CF
formulae.

HTH

"Suddes" wrote:

When using conditional formating i get the following message when trying to
use NETWORKDAYS' function

"you may not use references to other worksheets or workbooks for conditional
formatting criteria"
! any ideas why this would be the case

many thanks