There's no setting, but I wouldn't be terribly surprised if the code was optimized to handle the more common case of a horizontal panorama more adeptly.
Do they stitch properly if you turn each frame 90 degrees?
It's really about the content of the images. What's in the ones you can't get to stitch? Sky? You know there has to be enough overlap in the images that the software has to "see" patterns in the parts that overlap. Keep in mind that even things you think are pictured in the overlap area could be different enough from frame to frame (e.g., because the wind is blowing leaves or water) that the software can't see them as the same.
Could you post small versions of the files that won't stitch?
I will try I am not at home but thank you
its funny when i do lanscapes the layers show in landscape form and in portrait it shows in portrait but it has a image on the top and the bottom and 2 images stitched together in the middle. i thouught it would take up the whole pallet
thanks I will try to show you what i have maybe you can tell me how to show you my image
A screenshot showing the result at "fit to screen" zoom level might be enough to further judge what may be going on. You can attach images to forum posts using the web interface and the little "camera" icon just above the edit window where you type messages.
I've had vertical images fail to stitch as well, but usually it's because a frame is substantially water or sky, or in one case because the wind was blowing the branches of a palm tree, and while you and I would perceive it as the same palm tree, software looking at pixels sees two different ones.