15
Turn on debugging and see if you get additional messages when trying to update. Sometimes those errors will lead you to where the problem is. If you aren't sure, post them here (without personal path info)
If I understand correctly, you have an existing XOOPS 2.3.3 site with SmartSection 2.13 on it and you want to update to SmartSection 2.14 (or now 2.15).
Are you on a windows box or linux environment? Have you ensured that the file permissions for the new module files is the same as the set of files for 2.13. I have run into permissions issues in instances like this.
I'll have to look into the updated 2.15, although I know that SmartFactory is now heavily involved in the ImpressCMS effort and that XOOPS is now secondary thought to their development processes.
Odd that SmartSection 2.15 isn't listed at either SF or iCMS; apparently an updated version by Wishcraft and not official SF release (couldn't find anything about it in their forums).