php - Session variable not staying set -

warning: not duplicate, can't find problem.

i'm testing , building website on localhost. have following code on login page, sending user profile page if have user id cookie, , ip same cookies says should be.

if($_cookie["ipcookie"] == $_server['remote_addr']) {     $cookieresult = mysqli_query($connection, 'select count(`id`) count users username="$_cookie["usercookie"]" , `active`="1"');     if($cookieresult == 0) {         $loginquery = mysqli_query($connection, "select * users username=" .$_cookie['usercookie']);         $row5 = mysqli_fetch_assoc($loginquery);         $dbidlogin = $row5['id'];          $_session['userid'] = $dbidlogin;         header('location: /userprofile.php');     } 

however, when go user profile using these cookies, $_session['userid'] null. can't seem figure out why "sometimes" $_session goes null. can't seem find pattern in it. login 1 user, click links on profile page go different areas of website , go loginuser.php(the file shown above), , works 1 user, doesn't another. seems random, confuses me. can't think of reason change inbetween users. i'll continue test this, , see if can find pattern, several hours put in already, appears random.

my problem not appear answered of these:

php session data lost between page loads wampserver 2.0 on localhost -i checked php.ini, has lines of code (though different, functioning tmp file). example code in selected answer testing $_session variable works charm. code, doesn't.

php session not saving session_save_path() writable.

php session not being saved between pages php session data not being saved i'm on localhost, not server.

session_start(); on every page, excluding templates referenced in pages have session_start(); @ beginning (because if session_start(); in template comes error how session started).

update: may have pattern. users usernames including letters not have information saved. of these users have longer usernames, usernames words "dummy" , "eport" opposed "1" , "9." works 1 , 9, not dummy , eport. now, makes no sense, identified id's numbers, appear pattern.

update(the relevant code userprofile.php):

<?php  $userid = $_session['userid']; var_dump($_session['userid']);   //get. $totalquery = mysqli_query($connection, "select * users id='$userid'"); $arrayquery = mysqli_fetch_assoc($totalquery); $username = $arrayquery['username'];  //firstname $firstname = $arrayquery['firstname']; echo 'welcome ' .  $firstname; //lastname  ?> 

this bit of code nothing:

$cookieresult = mysqli_query($connection, 'select count(`id`) count users username="$_cookie["usercookie"]" , `active`="1"'); 

as $cookieresult loosely equal 0 (it false) when query fails. guessing need read data out of result resource handle gets set $cookieresult determine value count(id).