Hi everyone,
I have found problem with PHP Version 5.3.2-1ubuntu4.18. When I tried to submit a form, values appeared in $HTTP_RAW_POST but there was nothing in $_POST. Problem was in legnth of name attribut. In other PHP versions is this length virtually unlimited, but in this version is length of each array key limited on 64 characters. Hope that this information will help someone 
input type="text" id="text1" name="this_is_very_looooooooooooooooooooooooooooooooooooooooooong_name_which_will_not_submit_the_input" value="text"
Roman