Amazon EC2 cannot connect SSH via Ubuntu

Target machine is ubuntu, already set inbound rule for ssh at port 22 for all IPs(0.0.0.0/0). Result of ssh -v -v -i ladc2015.pem ec2-user@ec2-54-183-xxx-xxx.us-west-1.compute.amazonaws.com is:

OpenSSH_6.6.1, OpenSSL 1.0.1f 6 Jan 2014
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug2: ssh_connect: needpriv 0
debug1: Connecting to ec2-54-183-xxx-xxx.us-west-1.compute.amazonaws.com [54.183.128.207] port 22.
debug1: connect to address 54.183.xxx.xxx port 22: Connection refused
ssh: connect to host ec2-54-183-xxx-xxx.us-west-1.compute.amazonaws.com port 22: Connection refused

Already tried using public IP instead public DNS, already tested making all traffic inbound rule with all IPs, already used root, ubuntu instead of ec2-user as username. Still cannot connect. Please help, thanks.