New jersey uninsured policy coverage?

i was involved in a hit and run accident where my car was crashed into while parked and the person just fled the scene. my insurance company which is progressive is claiming they cannot do anything about it since i have limited liability. i told them about the fact that uninsured motor vehicle property damage is supposed to cover for cases of hit and run but they denied this saying that it would only apply of they find the person who did this and they dont have insurance. they told me this is the law in NJ. does anybody know anything about this because this is extremely unfair.