Connection impossible to Amazon EC2 : Permission denied (public key) - ssh

Question

I'm a bit lost with Amazon EC2. I just created an instance and generaited a pair of keys. I saved it on my win7 HDD.
I started a ssh connection through the terminal :
$ ssh -v -i EC2.pem instance_id#ec2-xx-xx-xx-xx.eu-west-1.compute.amazonaws.com
OpenSSH_4.6p1, OpenSSL 0.9.8e 23 Feb 2007
debug1: Connecting to ec2-xx-xx-xx-xx.eu-west-1.compute.amazonaws.com [54.76.160.55] port 22.
debug1: Connection established.
debug1: identity file EC2.pem type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_6.6p1 Ubuntu-2ubuntu1
debug1: match: OpenSSH_6.6p1 Ubuntu-2ubuntu1 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_4.6
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-cbc hmac-md5 none
debug1: kex: client->server aes128-cbc hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Host 'ec2-xx-xx-xx-xx.eu-west-1.compute.amazonaws.com' is known and matches the RSA host key.
debug1: Found key in /c/Users/FLE/.ssh/known_hosts:1
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Trying private key: EC2.pem
debug1: read PEM private key done: type RSA
debug1: Authentications that can continue: publickey
debug1: No more authentication methods to try.
Permission denied (publickey).
Doesn't seem to want to let me in.
When I try via putty, it answers Disconnected: No supported authentication methods available.
What is this ?
Thanks for helping.

Answer 1

Don't know the exact instance type you are trying to ssh into but the format should be "userid#ec2host.com" - you appear to be using instance id instead. Should look something like this:
ssh -i my-key-pair.pem ec2-user#ec2-198-51-100-1.compute-1.amazonaws.com
ec2-user is the default user for Amazon Linux, ubuntu is the default for all the ubuntu instance typers.
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AccessingInstancesLinux.html