Android :: Android Eclipse Error - Gson Cannot Resolved To Type

I'm relatively new to Java, eclipse and android so this could be a completely silly question, but I'm going to ask it none the less.

I've got a project I'm learning with to test connecting to the flickr api and simply displaying recent images. I'm at the point now where I want to parse the JSON received from flickr. I've downloaded gson 1.4 and added the zip to the java build path through "add external jars." It's successfully loaded and I can see google-gson under referenced libraries in the package explorer. My problem is, when I try to use it, I simply get an error.

Gson gson = new Gson();

It highlights Gson and says that "Gson cannot be resolved to a type." What am I missing here? It worked once and has since stopped. I've tried removing the jars, cleaning the project and re-adding the jars but it still doesn't work.