The response you are seeing is a default error response that the client object returns to the php application when the server did not respond to the call with a valid xmlrpc response.

The most likely cause is that you are not using the correct URL when creating the client object, or you do not have appropriate access rights to the web page you are requesting, or some other common http misconfiguration.

To find out what the server is really returning to your client, you have to enable the debug mode of the client, using $client->setdebug(1);