First please make sure you are using the latest official version of Daslight 4 (22.12.17 - links below).http://www.daslight.com/download.htm
You need to make sure the shutter is open and the dimmer up when playing or generating the Scene. You can either create a 1st Scene in Group 1 with just the shutter open and dimmer up. Then create 2nd Scene in Group 2 with a pixel effect and generate. Start Scene 1 then Start Scene 2 and you'll see your effect playing.
Or before creating your pixel effect open the shutter and dimmer up (or use the beam on button). The create you pixel effect and hit the 'include set levels' check box to include the values of channels 25 & 26 in your effect.