I can't understand why texi2any is missing while it's there

[Vittorio De Martino]

I'm trying to compile the R statistical program version 3.2.2  from the original sources under FreeBSD 10.2 but the installation program complains that:
>>>>>>>>>>
root at metbsd:/R-3.2.2 # make info
ERROR: 'texi2any' v5.1 or later needed but missing on your system.
*** Error code 1

Stop.
make[2]: stopped in /usr/ports/math/R-new/work/R-3.2.2/doc/manual
*** Error code 1
>>>>>>>>>>>>>
BUT:

>>>>>>>>>>>>>
root at metbsd:/R-3.2.2 # which texi2any
/usr/local/bin/texi2any
root at metbsd:/R-3.2.2 # texi2any --version
texi2any (GNU texinfo) 6.0

Copyright (C) 2015 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
>>>>>>>>>>>>>>>

I really acn't understand what's going on. Could you please help me?
Ciao
Vittorio