Importing tasks into tasklist in Milestone

Importing tasks into tasklist in Milestone

I've been trying to upload a csv file with tasklist names into a project with Milestones defined.
However, even if I enter the tasklist name in the correct field, it will just create a new Task list and I have to move all tasks over into the correct tasklist.
Is there a way to do it correctly?
My tasklist is called 'Gonio' under the Milestone 'Testing'.
My CSV is as follows:
"Task Owner","TaskListName","Task"
"UserA","Gonio","WO-10579"
"UserA","Gonio","WO-10580"

Any tips on how to fix this?

Thanks,
Menno