I've been getting the same errors on nearly every pano I shoot and I simply cannot figure it out.
Basically, using a D300 with Nikon 10.5, Nodal Ninja 5L. I'm shooting 7 around and 1 up.
Everything seems to go fine but the final product always has very small stitching errors with the zenith.
If I stitch without the zenith all is good. When I add the zenith I get errors near the top.
Any ideas? I'm not sure if it's a setup error, a control point error or a work flow error.