ช่วยหน่อยครับงมมาหลายวันแล้วไม่ได้สักที Fatal error: Call to a member function prepare() on a non-object in C:\AppServ\www\login.php on line 63

Fatal error: Call to a member function prepare() on a non-object in C:\AppServ\www\login.php on line 63

<?php
				if (isset($_POST['loginBtn']))
				{
					$username = $_POST['username'];
					$password = $_POST['password'];
					if (empty($username) || empty($password))
					{
						$show -> showError("กรุณากรอกชื่อผุ้ใช้และรหัสผ่าน");
					}
					else if (!ctype_alnum($username))
					{
						$show -> showError('Username has to be alphanumeric');
					}
					else if(strlen($username) < 3 || strlen($username) > 15)
					{
						$show -> showError('Username has to be 4-15 chars');
					}
					else
					{
						$SQLCheckUser = $odb -> prepare("SELECT COUNT(*) FROM `users` WHERE `username` = :user AND `password` = :password LIMIT 1");
						$SQLCheckUser -> execute(array(':user' => $username, ':password' => hash('SHA512', $password)));
						$loginCheck = $SQLCheckUser -> fetchColumn(0);
						if ($loginCheck == 1)
						{
							$SQLCheckBan = $odb -> prepare("SELECT `status` FROM `users` WHERE `username` = :username");
							$SQLCheckBan -> execute(array(':username' => $username));
							$banCheck = $SQLCheckBan -> fetchColumn(0);
							if ($banCheck == 0)
							{
								$SQLCheckExpire = $odb -> prepare("SELECT `expire`, `rank` FROM `users` WHERE `username` = :username");
								$SQLCheckExpire -> execute(array(':username' => $username));
								$ExpireArray = $SQLCheckExpire -> fetch(PDO::FETCH_ASSOC);
								if (($ExpireArray['expire'] > time()) || ($ExpireArray['rank'] == 1))
								{
									$SQLGetID = $odb -> prepare("SELECT `ID` FROM `users` WHERE `username` = :username LIMIT 1");
									$SQLGetID -> execute(array(':username' => $username));
									$_SESSION['username'] = $username;
									$_SESSION['ID'] = $SQLGetID -> fetchColumn(0);
									$show -> showSuccess('กำลังเข้าสู่ระบบ.. <meta http-equiv="refresh" content="2;url=index.php">');
								}
								else
								{
									$show -> showError('บัญชีของคุุณหมดอายุกรุณาติดต่อผู้ดูแลระบบ');
								}
							}
							else
							{
								$show -> showError('User has been banned');
							}
						}
						else
						{
							$show -> showError('ชื่อผุ้ใช้หรือรหัสผ่านไม่ถูกต้อง');
						}
					}
				}
				?>