I've lately been working on a piston door in Minecraft. It is almost finished and the only part that I have to add is the redstone signal elevator, but then it does something that leaves me confused. Here are two picture of the systems, which normally should be giving the same result.
The first one is the one which works...
And the second one won't work.
Both are powered by a button (it is necessary).
Here's the question: Is this a bug or it is normal? And if yes, normal, why?