Created Unassigned: Error registering task on Windows Vista [12469]

On Windows Vista, I can't register a task when a password is required.
The next code works on other operative systems, but not in Windows Vista:

TaskDefinition td = taskScheduler.NewTask();
td.Actions.Add(Application.ExecutablePath, string.Format("\"{0}\"", configPath));
td.Settings.DisallowStartIfOnBatteries = false;
td.Settings.StopIfGoingOnBatteries = false;

Task task = taskScheduler.RootFolder.RegisterTaskDefinition(taskName, td);
task.Definition.Principal.LogonType = TaskLogonType.Password;
task.Definition.Principal.RunLevel = TaskRunLevel.Highest;

TaskEditDialog editorForm = new TaskEditDialog(task, true, true);
editorForm.ShowDialog();

When clicking on OK button of the Task Edit Dialog, we are prompted to type password of the account. Even if the password is right, we get the error of the screenshot.