Hi. I have a shower pump which runs two showers. One shower (1) works fine, the other (2) has stopped working. The pump will only come on if I turn the other shower (1) on! (if I then turn the other shower off again, the shower(2) continues to work). My plumber has told me to get a more powerful pump. This is already the 2nd pump we have and it is approx 3-4 years old. When turning shower (2) on, no water comes out and the pump does not come on at all. Is there a problem the way shower (2) has been plumbed in?