cannot open google now I have Samsung Galaxy S2 Plus(GT-I9105) with rooted stock android 4.1.2.
So I thought of replacing touchwiz with Google Now Launcher. So, I installed Google Now from Play store. When I try to open it, It gives a message

"Touchwiz Home is currently your default launcher, go to settings, touch Clear Defaults and press the Home Button."

The problem is Touchwiz is not set to default (the button is disabled) as it is the only launcher I have.
Pressing Home button doesn't show Google Now Launcher.
I installed other launchers, and they work fine.Only Google Now has the problem. Is it a bug? Anything I should do?
You need to install the google search apk before the google now launcher