Pipe from waterpump to thermostat housing. Help!

Hello, a buddy of mine recently bought a polo 6n2 1.4. It was leaking from the thermostat housing so we replaced it and now we have a lot of trouble trying to connect the plastic pipe from the waterpump to the thermostat housing again. We have gotten the clip on with the pipe inside the housing but it still leaking and when feeling around it seems that its not fully inside the housing and therefore not sealed properly. But whenever we pull off the housing and try to get the pipe in all the way it keeps getting going out when the housing is screw into the block. It feels like the pipe isnt long enough to fully reach and seal.

Hope anyone can help us