Thaks for your answer!.

I've modified path so many times that i've lost count. Tried absolute and relative paths, different options, but with the same result. Permissions are granted to 755 in all folders from the root (i know it's not safe, but i'm just testing).

But now i think i've found an alternative. Using PGRFileManager and installing it outside the editors folder, at the same level it worked!. So, i'm confused and don't know what to do. I suppose it's a problem with the permissions, but i simply can't put all folders to 777, it'll be ridiculous.