There is an error when compiling ReactorChecker.cpp

I have read the chapter 9 of《getting started with LLVM core library. After coding the “ReactorChecker.cpp” , I execute “make” in my LLVM build directory(The version of my LLVM is 3.3,and I istalled it from source code). Then I got the error :

error: ‘void clang::ento::registerReactorChecker(clang::ento::CheckerManager&)’ should have been declared inside ‘clang::ento’

Anybody help me ?Thank you very much!