Make sure that the tap unit is placed correctly. Put the tap unit onto the connection top of the keg by pushing it down firmly ('CLICK' fig.1). If you snap the tap unit onto the keg correctly, it fits nicely between the two keg chimes.
Make sure the keg is placed correctly.
Lift the blue locking levers completely. Tilt the keg with the assembled tap unit forward slightly and put it into the appliance. Then push down the blue locking levers until they are in horizontal position.