Piston always activated

What I expected to happen was...:
If Sticky Piston has redstone block on it and you active it it stay Activated

What actually happened was...:
if the piston is up and there is a redstone block on it, when you put a button next to it and activate it, it will be on all the time

Steps to Reproduce:
1. put piston on ground
2. put redstone block on piston
3. activate it with button