What do you think? Do I stand a chance of winning my tort claim? Please help. ?

I filed a tort claim with the U.S. Department of the Interior on August 5th for $741.80 damages done to my car by vandals on July 28, 2008. The Dept. of the Interior said they denied the claim because damages to my vehicle did not result from any negligent act or omission on part of the Federal Government. To further explain, I was working for The National Park Service as a volunteer at the time of the incident. I came out to my car and found a broken window and damage to my trunk. I called the police after the incident and they arrived shortly after. The policeman said an incident occured there 2 weeks prior, when a Jeep Cherokee was broken into. I had no knowledge about this incident or I wouldn't have continued to do the volunteer work. The policeman also said that when the owner of the jeep reported the incident, that the N.P. Ranger came and took the report. So the ranger came and took my report. I filed the tort claim in August and it was submitted to the U.S. Dept of Interior. What can I do now? Just want to add, that I found out the day I filed my report that the other volunteer there quit working a few weeks before me because he thought it was too dangerous. Why didn't anyone tell me this? I can't afford to get the rest of my trunk fixed. Only fixed the broken window and the lock cylinder on the trunk. Also, they have no security guard, no security patrols, or security cameras in the parking lot of where I worked. Do you think I stand any chance of collecting my damages?