New Macro IN Operator

Has anyone gotten the new IN Macro operator to work? I just want to test it out and SAS Macro keeps coughing up an error that a character operand is found where a numeric operand is required.

According to the documentation, you can use the # character or the mnenomic IN. Their example is A#B C D E.

I am trying to test it with:

%macro test;
  %if A#B C D E A %then %put it works;
%mend test;
%test;

Pretty straightforward as far as I can tell. Am I overlooking something obvious?