Unable to Attach Object to Curved Wall

[Banksyde]

So I am trying to attach a tree branch to a curved wall, the wall is serving as a curved green screen, and the bounding boxes for the wall and the tree branch will not allow the two items to touch. I tried breaking the restraints by lifting each from the ground, but it doesn't seem to help. Not sure what is going on.

I have a iMac 2011 (old), 3.4 Ghz Core i7 OS 10.11

By the way, the Belzier handles on the curved wall are really cool. Nice feature!