Eclipse claims Commons-Codec methods don't exist

I'm working on validating the signed_request parameter from the Facebook API, following these guidelines, but I'm running into issues calling some of the methods of the Base64 class from Commons Codec. I added the commons-codec 1.6 library to my project (), but Eclipse is showing

and saying

which is odd, since this says otherwise.

I verified the md5 of the download, so that's not the issue.

Any bright ideas?

I suspect that you have another version of commons-codes classes in your classpath, before the commons-codec jar you installed.

Make sure the "Link with Editor" icon button at the top of the package explorer is pressed, and then ctrl-click on the Base64 type in your editor. Then check if the selected class file in the package editor is the class inside the commons-codec-1.6.jar, or if it's a class in another jar.