searching indices if menus don't work

[Karl Berry]

    search the indices of a file if following
    menus doesn't get anywhere. 

"info libc abor" finds
* aborting a program:                    Aborting a Program.  (line   6)

So I gather there is a substring match somewhere (which is good).

But then I tried "info emacs active" and it didn't match, even though
there is this index entry in the manual (for emacs 24.3, anyway):
* active region:                         Mark.                (line  13)

Can you reproduce that or should I go further?

Thanks,
K