Bug in AMD?

I am working for a company that delivers automated voice messages. Our main use of the asterisk is for speech recognition using AMD(). We are currently using the settings AMD(3500, 2000, 800, 6000, 100, 50, 4, 512). When we have analyzed our calls we have found that about 5 % of our calls detected as a machine with the error MAXWORDS-4-4 have been wrongly analyzed by AMD. It somehow detects that it is a human and plays the message. After a while it cuts the call and gives us the message error MAXWORDS-4-4, it sometimes cuts the calls after as long as 30 seconds. Do anyone else recognize this error?
Kind regards Elliot