Fisher & Paykel N395B - cold control tube protrude into circle?

Hi, I have just fitted a new thermostat (cold control) to our fridge but Im unsure of exactly how far along the end of the tube should sit. There is a hollow area in the evaporator which the tube inserts, and then there is a little cut-out in the shape of a circle - do I allow the end of the tube to protrude into this little cut-out area? Does it make any difference where the end of the tube is sitting?
Any help is much appreciated,
Chris :)