Not sure if this is related, but does the Data Definition "Cost Code Separator" have a value for the "Default Value" attribute?
When you define your formula, before you add any elements, you need to select the Delimiter pull-down at the bottom of the page. It defaults to None (), but you need to select one of the options. If it is disabled, that means you have already added element(s), and you need to click Clear All, then set the delimiter and then redo your formula.
Thanks to reply.
But this is Out of Box formula and i am not able to edit this formula.