Smarty folder permissions

[bmart]

Hello,

I need help figuring out the most suited folder permissions on a Prestashop 1.6.1.22, I'm trying to solve a login problem

Disabling Smarty cache (advanced parameters) there's something about the folder permissions that I can't figure out. I'm getting the following error:

"To use Smart Cache the folder must have write permissions."

even though in the server (root > httpdocs > cache > smarty) the folder has write permissions 775. All other folder in httpdocs > cache have 755:

the cache folder though, has 755 permissions

many thanks in advance, for any possible help.