Flex 3: SWC not loading in flex project!

Hi, I am running into this strange problem again and again in various flex projects - maybe I am repeatedly following some wrong steps. Someone pls guide me!

Whenever I download the source code from an internet location, and import that into my Flex workspace, I always get “unable to load xyz.swc” error. Where xyz is any swc file being used in that project.

E.g. I have got the source code (by right click -> View Source) of this cool custom component

But I get lots of error of different swc not loading. Though all the swc files are present in libs folder of the project!

Any clue?