My toilet wont flush?

Hi i have a toilet which has been built in and the button is on the wood unit surrounding the toilet.

Behind the button is a 5mm pip that pushes air to the toilet to make it flush. When we first moved in it took about 3 pumps of the button before it flushed so my partner cut the pipe shorter as he thought that having less distance to push the air would make it flush quicker. It now takes about 25 pumps to flush. We replaced the pipe back to its orignal length but still no luck. We have now taken the pipe of the button and we are having to blow down the pip to make the toilet flush how can we fix this???