These are hard cases, so it is best to talk with a local attorney. The good thing for you is the prior notice, The only problem could be low damages.
DISCLAIMER: David J. McCormick is licensed to practice law in the State of Wisconsin and this answer is being provided for informational purposes only because the laws of your jurisdiction may differ. This answer based on general legal principles and is not intended for the purpose of providing specific legal advice or opinions. Under no circumstances does this answer constitute the establishment of an attorney-client relationship.
often, businesses such as parking lots or garages have disclaimers on the backs of the tickets or on the contracts which attempt to limit the liability of the business for such claims. Some of these limitation of liability clauses are valid, and others are not. Still, it may be worthwhile to ask to make a claim against the business's insurance. There is a legal theory that one has no duty to anticipate a criminal act, but under the facts provided, there was notice of such criminal activity, which may make the parking lot liable.