There are multiple problems with your images that far exceed what Smartblend has to do with.
Your major problems are as follows:
- (NPP) No Parallax Point/Position is a long way out.
- Wrong and Mixed Aperture and Exposures.
- You will never get a decent result with things the way they are at the moment.
Please follow this tutorial for setting the NPP.
Please follow the instruction for shooting in this thread.
Basically you cannot use Shutter Priority and you also should not use Aperture Priority. Go completely (M) Manual Mode.
Do not change level (no re-leveling) or any camera settings in any one panorama set of images.
High ISO levels create and add noise/grain to the image.
Auto White Balance gives typically wrong white balance and may change the colour of each image between shots.
The Crop Circle should be set in such a way it is on the edge of the solid black area and the vignetted blur of the actual image.
Also the advice of tilting the camera/lens 5 degrees up (once you have found the correct NPP) is valid and will close the upper/zenith black hole.
Show me another set of images when you have completed the information provided.