Tree farm

Hi friends,

I made a tree farm on my Minecraft Bedrock realm. It seems that the double extender's aren't working and I'm looking at the redstone and am baffled.

I've rewatched the tutorial 6 times. Can anyone else figure it out? I've recorded a video of the redstone. This is the tutorial: https://www.youtube.com/watch?v=jm6YIIf1Vug&t=1043s

Thank you!