Camera Problem

I have a Kodak EasyShare CX7330 camera and recently it stopped working after a period of non-use. I assumed it was the battery and I took it to a shop to get a replacement. The guy in there tested a couple of batteries and none of them worked. He said the camera must be broken and it would be cheaper to buy another one.

Well when I got home I tried it with one of those universal ended plugs in a wall socket and the camera worked perfectly. Took a couple of pictures with no problem. So I can only assume it's a problem with the battery connections. Is there anything I can do or check or does this still mean that the camera is broken?

I have a plug at home which is like a replacement for any electronic item that runs off the mains electric. It has a lot of connectors for it and one of them fitted into the DC jack on my camera. It worked fine using that but it won't even turn on with just batteries.