Tower Plus EBT2250, stereo audio output

The rear Stereo Audio Line Out does not work (does not support my Dell AS500 Sound Bar - with a 3.5mm connection). Dell tells me that this back port will not support a universal jack? I'm not sure that I believe them (yet), especially since it works on my previous Dell Tower (that is, the same Sound Bar worked from the rear Stereo Audio out port).

Any ideas?