SHOWER AQUATRONIC 2 WONT LET ME DO THE COMMISSIONING ?

my last shower has just stoped working so i bought a new one its a aquatronic 2 (9.5)from wickes all iv changed about the plumbing side is iv put a flexy pipe on to the end near the shower the water is on and so is the power (tested with a light up screwdriver just to make sure) iv checked every thing i can think of (even the filter) but i cant get any water at all to come out of the shower please help before i drag it of the wall (only kidding) but please can any one help
thank you martin