Panorama Photo

My panos are always hand-held. No reason for such a tilt.

That's because of the stitching of adjacent images (done by PTGUI PRO).

We all here upload only multiframe stitched panoramic pictures. You have to do a horizon correction. In addition it is likely that you have some control points in the foreground. This makes rectification complicated. I would suggest to start with a easier subject
Kind regards Christoph