Connect Minecraft Redstone to Flask?

I have watched some videos about creating Xp farms where you have to connect redstone to piston. However, it always looks different. For me, the redstone doesn't connect to the pistons when I put it behind them. I play the 1.16.5

You have to make a repeater behind the piston in German redstone amplifier

Right behind? Because I always have them connected

So behind the piston then redstone then e.g. Lever

But then why does it work for others?

You may be doing it wrong

You've probably seen Redstone tutorials for the Minecraft Bedrock Edition. Redstone is very different there from Redstone for the Minecraft Java Edition, which you are probably playing, so you probably can't recreate the things from these videos directly.

If you want to put Redstone on a piston in the PC version, you have to put the Redstone directly on it. So not just behind it, but the last piece (on the last block) must point directly towards the piston.

Or long behind it, but a block higher. With full blocks as a base.

Right. That goes under, too, believe.

Nope under it doesn't work.

Not? It's been a long time.