I shot 8 photos around and one up and one down using the 16mm. Same as i've done in the past, but for some reason it's not stitching right. I've uploaded the images to the Box and can send you an invite to your email. You can email me at firstname.lastname@example.org
OK - some observations and comments:
1. You should disable the orientation sensor in the camera so that all images have a portrait orientation.
2. You seem to have used aperture priority auto, so your shutter speeds vary. Use full manual exposure and a fixed value for all shots. And f16 is too small an aperture, try f8. Fisheye lenses have huge depth of field at any aperture. You should use manual focus too, fixed for all shots
3. Because shutter speed varies APG 'thinks' that some exposures are bracketed and automatically out them in stacks. You will need to unstack the stacks.
4. APG doesn't recognise your lens as a fisheye - perhaps the EXIF was removed by processing images before stitching? So you need to set the lens type to fisheye in the image properties.
5. Because you have 8-around when 6-around is sufficient you have links created between non-adjacent images. Remove those superfluous links in the Panorama editor Control points editor and optimise.
Then you will find you get a good stitch.