[Solved] Only have ftp access with main user, impossible to create new ftp users that can connect


I am a total noob in all what is server tech. Actually I am more a frontend devigner ( designer + developer )
So I have this server setup with virtualmin and I can’t use the additional ftp users to connect to the server.

I am using Transmit to connect to the server through ftp and the message I am getting is:

Could not connect to server “ftp.netinspain.es”. The user name or password was not accepted by the server. The site may be inaccessible or your password may be incorrect. Please double-check your login settings.

I am using the same protocol (SFTP) and the same server (ftp.netinspain.es) for the main user and the (new) secondary user, but without success for the second one.

Those are the messages I find in the ftp log file, although I do not think they’re from my connections:
2016-09-23 04:52:42,402 mod_sftp/0.9.9[31374]: no available host keys, unable to handle session
2016-09-23 04:52:43,146 mod_sftp/0.9.9[31375]: no available host keys, unable to handle session

Thank you very much for your help

Finaly I found the answer here on the forum: