Training a horse involves creating a language between horse and rider.  It is very common for a horse to be somewhat guessing at the answer at times during this process. 
Your response to their best guess, is what helps them narrow down to the one correct answer. 
If you are consistent… This language includes your cue system: how you use your legs, seat, reins, voice…and the way you show up: focused, unfocused, etc. If your horse is unsure, he will often guess from some of the things they have most recently been rewarded for….or what he likes best.  NOTHING HAS GONE WRONG. You are refining a language with a HORSE. If you stay consistent, the horse will use a process of elimination to determine which answer is the correct one. If the horse is CONSISTENTLY guessing the wrong answer…then they are confused, then you must change something to help them get closer to the correct answer. Listen to this episode for the full explanation.