I've been flying trainers for a while now..and for some reason, I just can't get an aileron roll out of my superstar 40. I've tried up and down elevator at various points, as well as rudder both ways at various points, and all i can get is a half roll, then 90 degree snap straight down (like it's going to spin) then I have to up elevator and use the ailerons to correct back to level flight. I can do nice big loops, nice tight loops, marginal outside loops (gently), "hammerheads" (well , nearly, they still look neat), stalls, land and takeoff like a champ, but no stinkin aileron rolls!!!

Any ideas on how to practice this?