Task Scheduler Managed Wrapper does not show all tasks

Question

I have created a simple Windows Forms Application that displays the names and folders of all scheduled tasks on the machine. I'm using the Task Scheduler Managed Wrapper (Microsoft.Win32.TaskScheduler) and below is the code that gets the names and display them. However it seems as if AllTasks does not actually give me all tasks. There are some that are not displayed. What could cause a task to be hidden in this case?

using (TaskService tsksrvs = new TaskService())
{
    foreach (Task tsk in tsksrvs.AllTasks)
    {
        textJobsList.Text += tsk.Name + " (" + tsk.Folder + ")" + Environment.NewLine;
    }
}

Answer 1

The property AllTasks of the object Microsoft.Win32.TaskScheduler.TaskService returns only the Windows Scheduler tasks where the task's .Definition.Principal.UserId is either a user running the program Or System Or NETWORK SERVICE Or LOCAL SERVICE Or empty. By the way, it does not matter what value the property Definition.RegistrationInfo.Author has.

If you need to get ALL the task for ALL the users, you can accomplish it by the following code:

using Microsoft.Win32.TaskScheduler;
using System.Diagnostics;
using System.Text.RegularExpressions;
......................................
                Task[] allTasks = TaskService.Instance.FindAllTasks(new Regex(".*")); // this will list ALL tasks for ALL users
                foreach (Task tsk in allTasks)
                {
                    //Do whatever you need here, for example:
                    Debug.WriteLine("TaskName:{0}; Path:{1}; Author:{2}; Principal: {3}; ", tsk.Name, tsk.Path, tsk.Definition.RegistrationInfo.Author, tsk.Definition.Principal.UserId);
                }

Answer 2

As @nvoigt pointed out above the tasks not visible are running as a different user than the one executing the code.