Thanks a lot for your answer and instructions.
Sorry my mistake. I'm not very used to use forums.
Unfortunately, I'm still in doubt. I imagine that may have other users with the same doubt, so I decided to proceed the post, to complete the information to everyone. Sorry my insistence.
I follow this steps before post my first message.
Reading the FAQ Installation and upgrade section, I found:
"Can I upgrade from release 1.6.X to release 1.6.Z without intermediate upgrade to release 1.6.Y (provided that X < Y < Z)?
Yes, you can unless otherwise is explicitly noted in the release description."
Looking the release description of 1.6.15 version, I didn't find info about minimal previous version.
So, I thought that was possible jump from 1.6.4 to 1.6.15
In other hand, checking the update tab from my control panel, I found just up to 1.6.6 version. So, I think that it's possible jump just up to this version.
Before do anything, tried the forum help, because I wasn't sure about what do.
After my post answered, I updated to 1.6.6 version.
Everything is working, except the following error message, when I tried to update the database: "Checksum differs for /webim/README. Please, re-upload files to the server."
I already re-uploaded the files, but the message remains. However, my system it's working fine.
Now, after the update, my update tab is showing updates up to 1.6.15.
So, please give me some help about.
Best regards,