Error with wp-includes/http.php

Thank you,
I’ve tried to do both things, but does’nt work. In PHP.ini I’ve put this line:
memory_limit = 256M ; Maximum amount of memory a script may consume (64MB)

In wp-config.php this line:
define(‘WP_MEMORY_LIMIT’, ’64M’);

And when I put this line in the file that reports the error, my wordpress backend don’t work. Anyway.
define(‘WP_MEMORY_LIMIT’, ’64M’);

I thinl that maybe is a problem from the hosting provider, is it possible? What can I thell to them?

Thanks a lot!!