Item delivered USPS signature confirmation Customer saying didn't receive.

[Fabi1204]

Everything has been smooth until today. I'm so worried I lost the camera and will lose money, ending my very short career. I was going to ship priority mail like my auction started. Customer asked about delivery confirmation so I added it for free. Item arrives a couple days later and the customer said no way they never received. I looked at USPS and it says delivered to a person M.E. That's the initials of her 1st and middle name. I told her to call her branch immediately. I showed her pictures of what USPS showed me. She's requesting a copy of the signature. I never found it so I again told her to contact them asap. I've heard Ebay and paypal sides with the buyers. Is this true? Does it sound like a scam I'm not aware of? It's a 400$ digital camera. I'm leaving out of town and planned on using paypal for a hotel. I cant get out of town and see my $ freezing or being taken away so I'm trying to find comfort. I fear not offering insurance or even discussing it is my down call. Please any steps I can take? I've kept good communication through Ebay and I'm not jumping to conclusions but surely I'm not gonna lose the camera and the money??

[Fabi1204]

Should I open a case with paypal or Ebay? Or wait for the customer to do so. I feel the longer it goes, less chance of getting camera found. Also, where can I see it was signed and surely the postman isn't stealing things? Seems they could get fired for not actually getting a signature on a required signature mail