Session variable not passing through pages

[pug]

The page after I login displays Logged in as: username

Any page after that does. Does anyone know why it doesn't do it on the other pages?

<?
// include function files for this application
session_start();
require_once("include_fns.php"); 

$username = $_POST['username'];
$passwd = $_POST['passwd'];

if ($username && $passwd)
// they have just tried logging in
{
    if (login($username, $passwd))
    {
      // if they are in the database register the user id
      $valid_user = $username;
      session_register("valid_user");
    }  

    else
    {
      // unsuccessful login
      do_html_header("Problem:");
      echo "You could not be logged in. 
            You must be logged in to view this page.";
      do_html_url("login.php", "Login");
      do_html_footer();
      exit;
    }      

}

do_html_header("Home");
check_valid_user();

// give menu of options
display_user_menu();

do_html_footer();

?>

check_vaild_user on another pages displays who is logged in...Here is the code

function check_valid_user()
// see if somebody is logged in and notify them if not
{
  global $valid_user;
  if (session_is_registered("valid_user"))
  {      	
      echo "Logged in as: $valid_user";
      echo "<br>";
  }
  else
  {
     // they are not logged in 
     do_html_heading("Problem:");
     echo "You are not logged in.<br>";
     do_html_url("login.php", "Login");
     do_html_footer();
     exit;
  }    

}

[Weedpacket]

Try using $_SESSION['valid_user'] instead of $valid_user, and drop the session_register('valid_user').

So
$valid_user = $username;
session_register("valid_user");
can be replaced by

  $_SESSION['valid_user'] = $username;

and you won't get the problem of all the different values of $valid_user (from the session and from $username) stomping all over each other.

[pug]

When I replace that code in the member.php then it just displays

Logged in as:

It doesn't show the username that I used to login in with anymore even on that page

[pug]

Any other ideas?

Global variables are off. I'd like to keep it that way if possible

[Weedpacket]

Use $SESSION[] in the check_valid_user function as well ... replace $valid_user with $SESSION['valid_user'] (you don't need to declare it global), and replace session_is_registered('valid_user') with isset($_SESSION['valid_user']).

[pug]

Now I get this on the member.php pager after I log in

Fatal error: Call to undefined function: check_valid_user()

Here is that function, re-done the way you said

function check_valid_user()
// see if somebody is logged in and notify them if not
{
  $_SESSION['valid_user']
  if (isset($_SESSION['valid_user'))
  {
      echo "Logged in as $valid_user";
      echo "<br>";
  }
  else
  {
     // they are not logged in 
     do_html_heading("Problem:");
     echo "You are not logged in.<br>";
     do_html_url("login.php", "Login");
     do_html_footer();
     exit;
  }  

}

[hykc]

session_start() ???