IF function conditioned on a PARENT

What is a formula to count in a sheet summary the number of completed CHILDREN tasks per PARENT. For example, I wanted to count the number of competed tasks that fall under the parent of Business Development. I tried the following formula, but it did not work...For more context: The column called "Task Name" lists tasks fall into different PARENTS categories - the first of which is business development. The Status column marks if tasks are "Complete" or "In Progress" or "Not Started"

=COUNTIFS(Task Name:Task Name, PARENT([Busines Development]), Status:Status, "Complete")