Cooling hose connection fail

2005 X5 4.8is
Coolant reservoir had a split so picked up a new one and exchanged the old one. Mistake - can't reference the old one.

Lower hose (P/N 17127509966) connection leaks - really just drains the coolant as I add it. Wondering if there should be a washer/gasket on that connection to the reservoir (and the other two hose connections). I don't see any on the parts diagrams that I'm looking at online.

If not, any ideas why it is leaking? I have reconnected it several times, making sure it is fully pressed in and the lock clamp is secured.

Thanks!

Mike