Compiling [Linker error] undefined reference to...

[Xeikh]

Hello, im trying to add this feture:

luascript.cpp:

//doChallengePlayer(cid, target)
	lua_register(m_luaState, "doChallengePlayer", LuaInterface::luaDoChallengePlayer);

and...

luascript.h: (protected)

static int32_t luaDoChallengePlayer(lua_State* L);

But when i try to compile, it gives me this error:

[Linker error] undefined reference to `LuaInterface::luaDoChallengePlayer(lua_State*)'

Can please someone help me? :3