file_get_contents() and CI 3.0.0

when i was using file_get_contents() with CI 2, it was working as it should be as for the external pages (such as some_site.com) as for the internal pages (such as site_on_ci2.com), but with CI 3... for external file_get_contents() pages still works, for the intenal pages works but in a strange way, var_dump() shows that it contains the dom object, but when i try to fetch the elements, i get null, pls advice me how to fix it, thank u