is there mains voltage on the shower terminal block
if not the solenoid valve wont operate so no water flow can occur. check that the on/off switch is connected and the wires are connected ok.
be sure to check the condition of the mains switch pullcord contacts. if an old switch and the contacts are worn (very common problem) it could give the symptoms you mention on the new shower also on the old shower mira sport you replaced
garryk
February 2010