Greyhound lost/stole my luggage at Washington, Washington DC

I took a greyhound bus from New York City to Washington DC at 08/20/2011. With me 
was a suitcase(dark gray, brand: diplomat, one lock on side), which contains my 
passport, a laptop and some cloth. After I arrived DC, the greyhound failed to 
find the suitcase on the bus. Also, another gentleman could not find his luggage, 
either. I described them what my suitcase look like and what are inside the 
suitcase. Staff in DC called Baltimore Greyhound, and Baltimore said they found 
the two luggages(mine and anohter guy's) and would send them to DC with tags 
saying the destination (Washington, DC) by the next bus. At around 1:30 pm 
08/22/2011, the other guy got his luggage back and the DC greyhound staff told me 
they only received one luggage. After that, I rent a car at DC and went to 
Baltimore Greyhound but failed to find my luggage there. According to the DC 
staff's word, Baltimore sent TWO luggages for TWO persons to DC. What's more, the 
buses they used to deliver the luggage only travels between Baltimore and 
Richmond. I personally checked the unclaimed luggages of greyhound in Baltimore 
and DC, found nothing. According to the greyhound policy, they will always send a 
luggage with a destination tag to the destination. It has been more than 48 hours 
after I arrived DC at 9:00 am 08/20/2011, and before I called the greyhound center 
in Texas, DC greyhound did not even give me a claim number or something like that. 
Since the luggage should arrive DC and the truth is another person got his luggage 
which was shipped with my luggage on 08/22/2011, and only some of the staff at DC 
knew that I had some valuable things inside the suitcase, and the suitcase cannot 
always be on a bus.

I PERSONALLY think that it was the staff at DC Greyhound who 
stole my luggage.

At least they should admit that either they did not ship my luggage to the right 
place or one/some from greyhound stole my luggage.
(I kindly assume that greyhound can protect the luggages from being taken by other 
custmores.)