Redstone works not like expected

So i wanted to use redstone for the first time. i wanted to make florlighing. So i placed some redstone under the lamps and powered it.
but it didnt work. i consider this as a bug.

What I expected to happen was...:
the lighting would go on.

What actually happened was...:
the light stayed off.

Steps to Reproduce:
1. Place redstone wire under a lamp
2. power it.