During the quest, Way of the Voice, Master Borri teaches you a word of the Whirlwind sprint shout. He will whisper the word onto the ground, and for both Wuld and Nah, the dialogue plays correctly, but the Kest dialogue won't play if that's the word you're up to. This is because in the info topic for that dialogue (000c4371) the global used in the condition is set incorrectly. Instead of the condition checking if WWWhirlwind (0007096E) is set to 2, it is set to 1 by default, which is the value for Nah. This is confirmed by the other dialogue that uses this global matching the intended value. Simply changing the condition to check for a value of 2 will fix this, and cause the dialogue to play.