使用会话显示特定组的文本

This is a part of my session script:

$group='admin';

session_start();
header('Content-type: text/html;charset=UTF-8');
if(!isset($_SESSION['username']) and isset($_COOKIE['username'], $_COOKIE['password']))
{
  $cnn = mysql_query('select password,id,group from users where username="'.mysql_real_escape_string($_COOKIE['username']).'"');
  $dn_cnn = mysql_fetch_array($cnn);
  if(sha1($dn_cnn['password'])==$_COOKIE['password'] and mysql_num_rows($cnn)>0)
  {
    $_SESSION['username'] = $_COOKIE['username'];
    $_SESSION['userid'] = $dn_cnn['id'];
    $_SESSION['group'] = $dn_cnn['group'];
  }
}
?>

I want to show "blablabla" but only if you are in a group:

<?php
if(isset($_SESSION['group']) and $_SESSION['group']==$group)
{
?>
blablabla
 <?php 
 }
 ?>

In my table is a column named as "group". The group of this session is named as "admin" (that's why: $group='admin';) but it doesn't show the "blablabla".

Does someone know what I'm doing wrong?

if ($row= mysql_fetch_array($cnn))) {
 var_dump($var_dump); 
 $_SESSION['username'] = $_COOKIE['username'];
 $_SESSION['userid'] = $dn_cnn['id'];
 $_SESSION['group'] = $dn_cnn['group'];
}else{
 echo mysql_errno($cnn) . ": " . mysql_error($cnn) . "
";
}