Problem with my login screen

I created a mysql database, a connection in Dreamweaver, and a login page using the tutorials here on the Adobe site.  I thought I had followed everything according to the tutorials, using the "server behaviors" as instructed, but when I try to execute it, I get the following error:

Warning: mysql_select_db() expects parameter 2 to be resource, null given in C:\xampp\htdocs\IOD\loginToIOD.php on line 52

Warning: mysql_query() expects parameter 2 to be resource, null given in C:\xampp\htdocs\IOD\loginToIOD.php on line 57

Here's the code in that area of the page:

<?php
// *** Validate request to login to this site.
if (!isset($_SESSION)) {
  session_start();
}
$loginFormAction = $_SERVER['PHP_SELF'];
if (isset($_GET['accesscheck'])) {
  $_SESSION['PrevUrl'] = $_GET['accesscheck'];
}
if (isset($_POST['username'])) {
  $loginUsername=$_POST['username'];
  $password=$_POST['password'];
  $MM_fldUserAuthorization = "";
  $MM_redirectLoginSuccess = "WOTCPg1.php";
  $MM_redirectLoginFailed = "loginerror.php";
  $MM_redirecttoReferrer = false;
  mysql_select_db($database_LogIn, $LogIn);
  
  $LoginRS__query=sprintf("SELECT UserID, Password FROM authentication WHERE UserID=%s AND Password=%s",
    GetSQLValueString($loginUsername, "text"), GetSQLValueString($password, "text")); 
   
  $LoginRS = mysql_query($LoginRS__query, $LogIn) or die(mysql_error());
  $loginFoundUser = mysql_num_rows($LoginRS);
  if ($loginFoundUser) {
     $loginStrGroup = "";
    
    //declare two session variables and assign them
    $_SESSION['MM_Username'] = $loginUsername;
    $_SESSION['MM_UserGroup'] = $loginStrGroup;       
    if (isset($_SESSION['PrevUrl']) && false) {
      $MM_redirectLoginSuccess = $_SESSION['PrevUrl']; 
    }
    header("Location: " . $MM_redirectLoginSuccess );
  }
  else {
    header("Location: ". $MM_redirectLoginFailed );
  }
}
?>

The mysql database is named "InfoOnDemand".  It currently contains only 1 table, named "Authenticate", with just one record.  The table fields are:

UserID CHAR 30; Password CHAR 20; CustID CHAR 20 and Status CHAR 10 Default value "in" (that should be "out", but I haven't changed it yet).