I am trying to create a scheduled task but get not implemented error when I try to run it.

Class PICIS.Core.Tasks.CleanEntry Extends %RegisteredObject
{

ClassMethod ClearTasks(pBackupFile As %String = "d:\Temp\BackupTasks.xml", pDelete As %Boolean = 0)
{
// Create backup file
Set tBackup = ##class(%Stream.FileCharacter).%New()
Set tBackup.Filename = pBackupFile
Do tBackup.WriteLine("<?xml version=""1.0"" encoding=""UTF-8""?>")
Do tBackup.WriteLine("<Tasks>")