I have a mitel sx-200 mx controller with the latest software. I installed a 4150superset as my subattendant and programmed 2 LDN buttons. I can answer the calls just fine, but I cannot place them on hold and retrieve them. I programmed a hold position key, but when I hit the key it does nothing. A 4150 phone can do enhanced subattendant features, but this will not work. I do not know what I am missing.