You may have a Trespass to Chattel claim against her. She denied you access to property that was yours--plain and simple.
Unfortunately, in this particular tort, if you want compensation you generally have to prove damage. If you take her fat ugly neck-wagging bellybutton to court you will have to explain to the judge how your inability to access your camera cost you money, or prevented you from making money. That's for your compensatory claim. A punitive claim is another matter, and does not require a proof of actual damage. Duress, anguish, discrimination, all that good stuff comes into play there.
However, there is another way to approach this. She is an employee acting within the scope of her duties as an employee. The doctrine of Respondeat Superior dictates that her employers may be held responsible for her actions if such actions were committed in the course of, and in relation to her normal job functions. Therefore they very well may end up liable for her behavior, and any damages, either compensatory or punitive may fall on their shoulders. Their reaction to a demand letter, and the subsequent complaint is anybody's guess. If you get a real bastard of a lawyer (especially working on contingency), he'll also try to get them on negligent retention--but only if you prove malice.
In law school, the first thing they teach is that there is never a definitive answer other than the universal 'it depends'. What this will depend on is your lawyer, your judge, your jury, and, most importantly, your defendant. Get lucky and she'll never forget the day she laid eyes on you. Get unlucky and you'll only end up with your nerves frayed even more than they already are.
Good luck.
