Which is the highest probability? How close are the highest two selections? Are the images you provide for analysis more or less the same but with background clutter (you examples have no background). See Personal image classifier display .
Perhaps you need to enter more training images
or the PIC algorithm can not distinguish a small, relatively simple differences in the sign. What do you expect for free? Perfect recognition is probably impossible.
you might have better luck with TMIC . Try TMIC extension and let us know.
