There is one unfortunate reality that some people won't collaborate. Having said that... it is an easy out and as managers our job is to figure out the way to make it happen.
There is no simple answer... I would suggest you take a hard unbiased look at the "learning environment" you are creating. Is it the best learning environment for the other party? Perhaps you need to rethink how you structure that learning environment to acknowledge social and cultural norms that you have not thought about.
Perhaps the jump from where you are currently in the relationship to where you want to be is too drastic.. maybe you focus on taking what I would call "baby steps" in an effort to gain buy in, build relationships and achieve your goal.
Perhaps you can enlist peers to support your effort.
It is easy to say it is too hard, and it is very difficult.. but remember that when you are working with an International Team sometimes you have to go to them before you can get them to come to you. In other words... focus on the cultural aspects of why they are doing what they are doing and overcome those gaps by acting and doing something more familiar to them..
It won't be easy, but if you can get it you will be setting yourself apart from many others who can't do that successfully.
Good luck and would love to hear how it turns out, or keep us updated along the way.