In in each scene I'am staring and stoping physics and everything is ok.
When I tried to change physics.setGravity(0,40) different for each scene it doesn't work. crash.
any idea ?

Sorry , you can change a gravity in each level but you have to use something like "loading page"
I thought I can change from level.lua to level2.lua but it's the same problem when you try to repeat level.
So the problem was with "loading page".