AME AP Invoice Approval not working for HR Position

Hi,

I am trying to implement AME for AP invoice but I stuck in the end; I just follow below steps:

1. define action type as approval-group chain of authority

2. define approver group as HR position

on test the work flow every thing work find,

one use a specific hr position and test on application its work great,

any other position type I got no exceptions no errors, but never return notification for the user who assigned to the job position

I cannot find the different between the success job position and the others, or between the success employee and the