AKG mics do not work in RJtech karaoke/dvd machine

by Art
(Tucson, AZ USA)

I bought an RJtech RJ-4200 DVDplayer/karaoke machine just like the one my son has. I wanted to upgrade the microphones, so I purchased 2 AKG D 88 S mics. When In connected them to the XLR/1/4" jack cable AND turned the switch ON, the mics did not work at all. Everything I tried was futile.

I talked to the tech where I bought the mics and he said maybe the gain was not high enough. He thought maybe I should be a preamp. I did not do that.

I called the manufacturer and got very little help. In fact, I was told the tech support guy was out of the office and would call me back. No call, obviously.

What do you think might be the problem? Propriety mics?