Hey there, Dwayne,
Sorry to be so long to reply.
I took a look at your synth and the four images that weren't connecting to the rest of the synth were images 1, 2, 142, and 143.
1 and 2 had matched each other but nothing else and 142 and 143 had matched each other but nothing else.
Just looking at it, I thought that since the monument was so small in those photos, that perhaps I would try an old trick from the Photosynth team ( https://getsatisfaction.com/livelabs/topics/don_t_crop_images#reply_585680 ) and make a copy of those photos and crop the copies to give Photosynth a little better look at the tower in those shots.
The idea is that the crop will match its parent image and if the crop connects to others in the synth, then the parents will connect to the rest of the synth via the crops.