Fixed flashmessage, it uses write not set

controllers/UsersController.php

@@ -326,7 +326,7 @@ class UsersController extends \lithium\action\Controller {
 			}
 			else
 			{
-				FlashMessage::set('Username or Password Incorrect.');
+				FlashMessage::write('Username or Password Incorrect.');
 			}
 		}
 	}