Got xhtml page

[Preovaleo]

hello;

i got phplist v3.2.4
and when i try the demo script at the end of the readme i got

PHP Notice: Trying to get property of non-object in example.php on line 17
PHP Stack trace:
PHP 1. {main}() example.php:0
example.php:17:
NULL
PHP Notice: Trying to get property of non-object in example.php on line 31
PHP Stack trace:
PHP 1. {main}() example.php:0
example.php:31:
NULL

i investigate a little and find out that the curl retrive an xhtml page and not a json.
Do i make something wrong?