generally speaking, your asking a lot from the chamfer and fillet commands. these are for final edge treatment, and not form creation. Not to say they don't get used that way all the time, but they don't really shine in that capacity.
but before that even, when you moved the body together you created a veeeeeery tiny little lip (you can see when I measure the distance between the 2 surfaces in the screen cast). geometry like that wreaks havoc on fillet and chamfer type commands.
in the screen cast I used the align to command to get the bodies aligned without that little lip. you still probably can't completely do what ever it is your trying to do, but it should work a little better.
generally speaking though, in a parametric model you won't ever use move or align commands like this. sketch and build things where they are suppose to be from the beginning, and you will save your self a lot of grief down the road. and maintain the hope of having a stable parametric model at the end.
https://knowledge.autodesk.com/community/screencast/828613b5-d297-4454-9179-49e149fb0ffd
