h2ouston's bottom up drills, need comments on vertical kick

hi, yesterday i tried the h20uston's bottom up drill part one www.h2oustonswims.org/articles_whole.html i can kick powerfully and efficiently when gliding on the back. 1/ when i do vertical futter kicking i sink almont immediately. there must be something wrong with my kick. what are the typical sinking mistakes when vertical futter kicking? 2/while vertical kicking you are supposed to produce a rotation kick in order to rotate 45 deg. this kick will be used when breathing in front crawl. I just cannot produce such a kick when streamline kicking. can you elaborate on how to produce such a kick. thanks for comments.