You don't need the extra 'object' wrapper around your #declared objects...
#declare MyBox1 = object { box { <-1, -1, -1>, <1, 1, 1> inverse } }
could be written as
#declare MyBox1 = box { <-1, -1, -1>, <1, 1, 1> inverse }
It will still work the same when used as
object{MyBox1}
It has nothing to do with your 'problem' though...
