As seen on the pictures, you can't place a Redstone Dust/Carpet in the space where the cursor in the photos is pointing on. When you put a block then you added the block with some Item Frame then you try to put the Redstone Dust/Carpet in the space like the ones in the photos where the cursor is pointing on, it can't be placed there. This is definetly not Work as Intended because it is clear that it is a bug! In other Minecraft you can place the Redstone Dust in the space that I am talking about, while in MCPE you can't place it there. I hope that it will be fixed soon.