Hello,
Several things to say, first note that your HikaShop version is a 2.3.1 and so very old... Plus, use it with a recent Joomla may be a little touchy...
As you can imagine we don't support anymore this version, because it close to impossible for us to solve most of issues
Note sure this will work with a more recent plugin.
Where did you get your Atos Sips plugin ?...
I don't think it's from the HikaShop built in, because so far, we don't know from where did come this kind of error...
Regards
[Moderator :]
Please do not post the same message more than once, of course, it need some delay to help everybody.
Thanks for your attention