I have two buttons programmed on my phone; "Cover Msg Ret" to view messages on peoples extensions and "Canel LWC" to delete message so to turn off the message waiting lamp. Is this the correct way to check somones extension for messages - at the phone level? If so, why do I get, "message retrival denied" when I press the Cover Msg Ret and dial the extwnsion I want to check for messages?