Forge + Digital Ocean, I can't deploy

I create a new server, I create a new site, I add the github repo, I add the ssh key from the site to the repo, and I go this message:

Something went wrong when we tried to execute an action on your server. Sometimes this means we couldn't SSH into the server, or something may have gone wrong while executing a command. If error output is available, please review it below.

Please make sure that the following SSH key is placed in both the /home/forge/.ssh/authorized_keys file and the /root/.ssh/authorized_keys file on your server.

so, what's the problem?

is the first time that I can't deploy, I didn't have problems with other server/sites. I miss something this time?