Pet System Client Source error

> PythonApplication.obj : error LNK2019: unresolved external symbol "public: virtual __thiscall CPythonSkillPet::~CPythonSkillPet(void)" (??1CPythonSkillPet@@UAE@XZ) referenced in function "public: virtual __thiscall CPythonApplication::~CPythonApplication(void)" (??1CPythonApplication@@UAE@XZ)
2>PythonApplication.obj : error LNK2019: unresolved external symbol "public: __thiscall CPythonSkillPet::CPythonSkillPet(void)" (??0CPythonSkillPet@@QAE@XZ) referenced in function "public: __thiscall CPythonApplication::CPythonApplication(void)" (??0CPythonApplication@@QAE@XZ)
2>PythonApplication.obj : error LNK2019: unresolved external symbol "public: bool __thiscall CPythonSkillPet::RegisterSkillPet(char const *)" (?RegisterSkillPet@CPythonSkillPet@@QAE_NPBD@Z) referenced in function "bool __cdecl LoadLocaleData(char const *)" (?LoadLocaleData@@YA_NPBD@Z)
2>PythonApplication.obj : error LNK2019: unresolved external symbol "public: void __thiscall CPythonSkillPet::Destroy(void)" (?Destroy@CPythonSkillPet@@QAEXXZ) referenced in function "bool __cdecl LoadLocaleData(char const *)" (?LoadLocaleData@@YA_NPBD@Z)

2>UserInterface.obj : error LNK2019: unresolved external symbol "void __cdecl initskillpet(void)" (?initskillpet@@YAXXZ) referenced in function "bool __cdecl RunMainScript(class CPythonLauncher &,char const *)" (?RunMainScript@@YA_NAAVCPythonLauncher@@PBD@Z)