You must use a post from the 4thxs directory. Normal posts do not support indexing.
The post CNC files have the indexing axis hard coded. Most are setup to rotate about the X axis. The axis of rotation in your program must match the rotation axis of the post.
If you are using multiple setups and are rotating about the world X axis the X axes of the setups must be parallel to the world X axis.
If you are using multiple setups and are rotating about the world Y axis the Y axes of the setups must be parallel to the world Y axis.