首次登录时不会创建php会话

Question

I have a problem setting up a session. Every time i commit log in to the site the session should be created, but it isn't so and i am redirected to notvalid.php. The session is created only the second time i try to log in

session_start(); is the first line at every page at my website.

This are the connection functions:

public static function Login($name, $pass)
    {
    if (!empty($name) && !empty($pass))
        {
        global $dbh;
        $result = $dbh->query("SELECT * FROM users WHERE username = '" . $name . "' AND password = '" . $pass . "'");
        $row = $result->fetch(PDO::FETCH_ASSOC);
        if ($row > 0)
            {
            $userid = $row['userid'];
            $_SESSION['userid'] = $userid;
            $_SESSION['login'] = 'true';
            echo '<META HTTP-EQUIV="Refresh" Content="0; URL=userindex.php">';
            }
          else
            {
            echo "incorrect username or password.";
            $_SESSION['login'] = 'false';
            }
        }
    }

this function check if the session exist:

public static function checklogin()
    {
    if ($_SESSION['login'] == 'true')
        {
        return $_SESSION['userid'];
        }
      else
        {
        echo '<META HTTP-EQUIV="Refresh" Content="0; URL=notvalid.php">';
        }
    }

I have tried to enter the site with or without www, i have tried to do as they suggest here

PHP login session wont work on first page load in a NEW window with no cache

But nothing helped.

Any help would be graet.