Does she understand the gentle command fully? Are you using it with food or anything else?
I start the command with food and then use it in other settings and the dog quickly understands that the command can have two parts, doing the obedience but under control. You can use it to moderate play and anything really, simply be firm and consistant and the dog learns that getting the reward involves self control as well as the command itself
I hope that makes sense.
I wouldn't reward even if the obedience is right if she's doing it too roughly, maybe a quiet "good girl" at the beginning but quickly I would escalate my expectations so no jackpot until the lid is touched gently, she'll catch on quick on what gets the best results from you.