SSH connection doesn't work properly

after signing all the things, and also generated an ssh key, and executing "/path/to/dropbear -r /var/dropbear_key" (the key i generated), if i try to connect to ssh with "ssh root@localhost -p 2222" it gives me: "Connection closed by 127.0.0.1 port 2222", idk a lot about networking, i'd like to know why could this happen, and eventually how to fix it.
thanks in advance!