UNPROTECTED PRIVATE KEY FILE Error using SSH into Amazon EC2 Instance AWS

Question

I've created a new Linux instance on Amazon EC2, and as part of that downloaded the .pem file to allow me to SSH in.

When I tried to ssh with:

ssh -i myfile.pem <public dns>

I got:

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ @ WARNING: UNPROTECTED PRIVATE KEY FILE! @ @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

Permissions 0644 for 'amazonec2.pem' are too open. It is recommended that your private key files are NOT accessible by others. This private key will be ignored. bad permissions: ignore key: amazonec2.pem Permission denied (publickey).

I tried to chmod +600 the pem file, but now when I ssh I just get:

Permission denied (publickey).

What error am I making here? The .pem file is in my home folder (in osx). It's permissions look like this:

-rw-------@ 1 mattroberts staff 1696 19 Nov 11:20 amazonec2.pem