u/SaberPS

Hi, I'm new to fighting games and Chun is my first main. I have a combo I practiced where I do heavy kick into serenity stream medium kick and then OD lightning legs into SA2, but the fact bison gets knocked up here completely threw me off and every time I try to repeat this effect on the dummy it doesnt happen? Is there something else going on causing him to go up in the air I need to be aware of? Thank you for help in advance!