I need some help with own adding files(.h ) to code base to resolve undefined reference problem .

  CXXLD    bgoldd
/usr/bin/ld: libbitcoin_consensus.a(libbitcoin_consensus_a-interpreter.o): in function `EvalScript(std::vector<std::vector<unsigned char, std::allocator<unsigned char> >, std::allocator<std::vector<unsigned char, std::allocator<unsigned char> > > >&, CScript const&, unsigned int, BaseSignatureChecker const&, SigVersion, ScriptError_t*)':
src/script/interpreter.cpp:457: undefined reference to `Context::getDefault()'

I have do some modification in src/Makefile.am but no effect. Can anybody give some work example of this Makefile.am ?