As @andresrc rightly says, for security reasons, phpMyAdmin is accessible only when using 127.0.0.1 as the hostname. To access it from a remote system, you must create an SSH tunnel that routes requests to the Web server from 127.0.0.1.
Taking a look at the following guide you can find some instructions about how to connect to phpMyAdmin from Windows, Linux or OSX:
Please let us know if this solves the issue.
Carlos R. Hernández