Thank you, stokerg, for the quick reply. The problem has been solved.
And I know I must say that it was not Affinity Photo but I that had some sort of problems.
As I said in the query section, my pictures didn't stitch no matter how many times I tried, even after I deleted AP and reinstalled it on my iPad. And I took pictures all over again, and it didn't work.
Then, I thought that, maybe, my pictures were all wrong from the start. My understanding of "overlap" was that, for stitching, each picture was to have some parts in the areas, far-left or far-right, to stitch, which were the same objects or people and that was enough for me.
But, that wasn't enough. Through a couple of more tries, I found out that, even AP does a very wonderful job, to stitch seamlessly, each area must have objects that look quite the same or at least similar.
What I mean is that, when taking pictures for a panorama, just holding a camera still and moving my body slowly is not enough. I must take into account the fact that moving my body even slightly can create a different angle of an object and a distorted or crooked version of it, which didn't happen in the first photo and doesn't help pictures to stitch seamlessly.
Thank you again for the quick reply and I respect all the works and efforts that you guys at the Serif make to make this great App even greater.
Thank you.
Eric from South Korea.