problem: the sphere doesn't go down

hi all!
looking the samples, i tried to make a sample to practice with the ode and ogre...
I created a plane and a sphere, the sphere is over the plane...i wish to view that the sphere go down to the plane...
but the sphere is still fixed over the plane...
i think that my problem is the code in the listener:

bool TestFrameListener::frameStarted(const FrameEvent &evt)
{
_world->updateCurrentState();
return true;
}

but doesn't work...

thanks

you need a stepper. look into the demo codes, there you will find it somewhere.