Its funny…I actually have hosting accounts at two different places. one of them is 000webhost and all of my blogs there will not authenticate but this one VoIP Review Twitter is hosted on a different, paid host and as you can see, it is working with no problem. This makes me believe that the plugin is fine but the host is the problem.
As someone said above, curl is required and it seems to me that there is some php setting that is preventing it from working on certain servers.