Excluding 'Apply Concession' function from a responsibility

 Dear Projects Gurus,

We are in 11.5.10.2 and I am trying to exclude the 'Apply Concession' radio button(function) from within the Credit functions of Projects Invoice. However, I am finding that there is no function with that name to exclude, though the other two functions (Cancel Invoice and Write-Off) are available to be excluded in the Function Exculsion area of the Responsibility Definition.

Can anyone please let me know how this can be accomplished because we do not want the users to 'Apply Concession' at anytime and want to remove that atogether from certain responsibilities.

I appreciate  your feedback.

Thanks and regards