on demand not available

I have always been able to watch Local Channel Shows On Demand ...  the past 2 days - I tag the show I want ( ABC - 911, Will trent ) the Title comes up - the Time line shows on the bottom of screen .. but then it is Black  Screen ... Nothing happens , nothing plays, I have "chatted" with Assistant, I have "chatted" with a representative - they have refreshed my system, I have rebooted my box .. still nothing .. has anyone else experienced this issue ? It is ONLY ABC ... CBS & NBC , etc.. seem to be fine.