Transition with Alphachannel and mp4 doesn't show up.

[genccares2020]

I wanted to input a transition between two scenes. This transition layer has transparency and at this transparency I want to show the beginning of next scene. The next scene is right below this transition, but for some reason the layer below is not visible (the transparency pattern is showing). Instead of the layer below with my video data in mp4 data type i tried also with a solid coloured layer and this seems to work. Why the solid show in that transparency area any my video do not. Pls help

Thanks in advance. 

[Mylenium]

Start by checking your hardware acceleration settings and update your graphics driver. for anything beyond that, actual info about your system, your settings and even screenshots may be required.

Mylenium