How to Change Transition Time with ExtendScript on Premiere

I want to add transition between two video. I want to use Extendscript for this, because there are too many video couple. I can create new sequence, add clips to sequence and add transition between them. Extendscript adds transition as two seconds as default. I need to change this as 0.5 second.

When i write this codes, it gives me "2" as result. $.writeln(app.project.activeSequence.videoTracks[0].transitions[0].duration.seconds);

I am trying this;
app.project.activeSequence.videoTracks[0].transitions[0].duration.seconds = 0.5;

But result is "2", again.
$.writeln(app.project.activeSequence.videoTracks[0].transitions[0].duration.seconds);

How can i do this?