Link errors when creating a PostProcessVolume c++

Hello I am trying to create a PostProcessVolume in c++ so I can create some custom functions for it. But when I create one the build starts spitting out a bunch of Link errors as seen below.

2>     Creating library F:\Unreal\Remembrance_Prot\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-Remembrance_Prot.lib and object F:\Unreal\Remembrance_Prot\Intermediate\Build\Win64\UE4Editor\Development\UE4Editor-Remembrance_Prot.exp
2>StylizedFogVolume.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl APostProcessVolume::PostUnregisterAllComponents(void)" (?PostUnregisterAllComponents@APostProcessVolume@@UEAAXXZ)
2>Remembrance_Prot.generated.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl APostProcessVolume::PostUnregisterAllComponents(void)" (?PostUnregisterAllComponents@APostProcessVolume@@UEAAXXZ)
2>StylizedFogVolume.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl APostProcessVolume::PostRegisterAllComponents(void)" (?PostRegisterAllComponents@APostProcessVolume@@MEAAXXZ)
2>Remembrance_Prot.generated.cpp.obj : error LNK2001: unresolved external symbol "protected: virtual void __cdecl APostProcessVolume::PostRegisterAllComponents(void)" (?PostRegisterAllComponents@APostProcessVolume@@MEAAXXZ)
2>StylizedFogVolume.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl APostProcessVolume::PostEditChangeProperty(struct FPropertyChangedEvent &)" (?PostEditChangeProperty@APostProcessVolume@@UEAAXAEAUFPropertyChangedEvent@@@Z)
2>Remembrance_Prot.generated.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl APostProcessVolume::PostEditChangeProperty(struct FPropertyChangedEvent &)" (?PostEditChangeProperty@APostProcessVolume@@UEAAXAEAUFPropertyChangedEvent@@@Z)
2>StylizedFogVolume.cpp.obj : error LNK2001: unresolved external symbol "public: virtual bool __cdecl APostProcessVolume::CanEditChange(class UProperty const *)const " (?CanEditChange@APostProcessVolume@@UEBA_NPEBVUProperty@@@Z)
2>Remembrance_Prot.generated.cpp.obj : error LNK2001: unresolved external symbol "public: virtual bool __cdecl APostProcessVolume::CanEditChange(class UProperty const *)const " (?CanEditChange@APostProcessVolume@@UEBA_NPEBVUProperty@@@Z)
2>StylizedFogVolume.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl APostProcessVolume::Serialize(class FArchive &)" (?Serialize@APostProcessVolume@@UEAAXAEAVFArchive@@@Z)
2>Remembrance_Prot.generated.cpp.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl APostProcessVolume::Serialize(class FArchive &)" (?Serialize@APostProcessVolume@@UEAAXAEAVFArchive@@@Z)
2>F:\Unreal\Remembrance_Prot\Binaries\Win64\UE4Editor-Remembrance_Prot.dll : fatal error LNK1120: 5 unresolved externals

The PostProcessVolume.h is included in the headerfile. I have no idea what is wrong so if anyone have any knows how to solve this it would be much appreciated!

same error here. please help!