turn on right knob (1) and see if water come out from main line. If no water flow - open the main on/off valve for water supply (3 & 4). If still no flow, problem related to the water line not related to system.
If water flow from the right knob (1), open valve located in safety group (5), and if filter assembled tighten filter into the holder (6 & 7).
Wrong In/Out water pipes connection,need to switched the pipe connection (9,10)