How to correctly use Control Linking in Kontakt?

I can't for the life of me work out how to get this to work. Here's the scenario:

Load up Kontakt. Load up an instrument from whatever library. Bind a bunch of hardware controls to software controls. Now change that instrument to another one from a different library and bind those hardware controls to that instruments' software controls. Doesn't work.

I thought maybe this is because it's taking that Kontakt instance as the focus rather than the instrument itselt so won't reassign. So i load up a new Kontakt instance on a new track and try again. Still doesn't work.

What trick am i missing here? Can someone shed some light?