how do i get my push button to work?

my push button is conected to an addaptable hose but resists to flush, my toilet is on a wall hung system from grohe, the button is not doing anything.please advise on how to get button to flush and more water to flow out of toilet, when i apply pressure to the ball cock a little trickle of water runs down the back of the toilet, thus not strong enough to push a single piece of toilet paper down