A child can decide not to see a parent at any age but if you do not force the child to see the parent then you could be violating a court order and could be in trouble yourself.
The child doesn't legally have to see the parent or go with them but legally you have to force the child to see them but the child won't get into trouble but you as the parent would.
Once the child reaches 14 years of age and beyond though then a judge will understand that you cannot really do much to get the child to go with their parent and you won't be in trouble.
If the child is refusing to see his or her parent when they are required too you should let the judge know about it so that you don't get into trouble.
But you need to try and force the child to go with the parent as long as they are under age 14.