Apple tv/iPad combo and powerpoint problems?

The problem occurs when I connect my iPad with Apple tv. After I open several powerpoint presentations in the powerpoint or keynote app, I will get a black screen on the beamer or tv. It only occurs when I'm in presentation modus in the powerpoint/keynote. If I close the presentation modus, then the screen comes back again and I see the mirrored iPad again on the screen. Can anyone help me with this problem?