Optimization functions undefined

[RICHARD Dominique]

Hello,
    I am coming back to an optimization code which used to run smoothly few months ago with Octave 3.8
When I try to rerun it today on a new machine with Octave 4.0.0 and optim package 1.4.1,
 I get the following error :
'fmins' undefined near line xxx

So I checked and this function is on my machine in /usr/share/octave/package/optim-1.4.1/ as expected.
In this same folder I found what seems to me like test files and I tried to run : test_min_1.m
and this time got the error :
'__bgfsmin' undefined near line xxx

What's wrong with my installation ?
How could I get my optimization code to work as it used to ?

Thanks,

--
Dominique RICHARD
Laboratoire de Génie des Procédés Catalytiques - CNRS-CPE Lyon
3, rue Victor Grignard F-69616 Villeurbanne cedex
Tél. (33) 4 72 43 17 52 - Fax (33) 4 72 43 16 73