need some help on my backroll

Been wakeboarding for about a year and a half now and have alot of basic tricks done (180s, grabs, 360s, riding switch) Now im working on a HS Backroll, from some pics of myself and what everybody is telling me is im not getting any air when doing this, ill get upside down and just lose it from there. Ive worked on keeping the rope close to my front hip when rotating but I just cant seem to get air when do this. I ride behind an 11' Axis a22 with 3k ballast and wedge. I always get sick air doing anything else but this backroll. Could use some help guys! thanks