The error [ Couldn't load hellocpp: findLibrary returned null]

Hello.
I started the cocos2d-x android, so I installed android-ndk, cocos2d-x, etc…
I compiled sample code, but it didn’t run. I can’t find a solution this error.

11-27 14:34:05.533: E/AndroidRuntime(2497): Caused by: java.lang.UnsatisfiedLinkError: Couldn’t load hellocpp: findLibrary returned null

any solution to the above problem?

Have you succeeded building native codes?