Krups Nespresso FNA2 coffe/cappucino machine

Question

Hi - this machine can make espresso or cappusino coffees - as such there are 2 buttons (1 small cup and 1 large cup on the right handside to choose whether you are making an espresso or cappucino coffee. The difference is that the nespresso button delivers less water than the cappucino button for example.The problem is that when I pres the button indicating I want to make an espresso, the water does not stop flowing. So, it seems that whatever triggers the machine to measure the amount of awater needed doesn't work.