Error in create new classs

hi.
I start with unreal programming tutorial in youtube
when I create a pickup class , visual studio get me some error :

Error 1 error C2065: ‘baseCollisionComponent’ : undeclared identifier ***\TestThirdTwo\Source\TestThirdTwo\Private\Pickup.cpp 12 1 TestThirdTwo

Error 2 error : Failed to produce item: ***\Unreal Projects\TestThirdTwo\Binaries\Win64\UE4Editor-TestThirdTwo-Win64-DebugGame.pdb ***\Unreal Projects\TestThirdTwo\Intermediate\ProjectFiles\ERROR TestThirdTwo

Error 3 error MSB3073: The command “”***Unreal Engine\Launcher\Engine\Build\BatchFiles\Build.bat" TestThirdTwoEditor Win64 DebugGame ***\Unreal Projects\TestThirdTwo\TestThirdTwo.uproject"" exited with code -1. ***\MSBuild\Microsoft.Cpp\v4.0\V120\Microsoft.MakeFile.Targets 38 5 TestThirdTwo
4 IntelliSense: no instance of constructor “FReadSurfaceDataFlags::FReadSurfaceDataFlags” matches the argument list ***\Unreal Engine\Launcher\Engine\Source\Runtime\Engine\Public\UnrealClient.h 55 92 TestThirdTwo
5 IntelliSense: no instance of constructor “FReadSurfaceDataFlags::FReadSurfaceDataFlags” matches the argument list ***\Unreal Engine\Launcher\Engine\Source\Runtime\Engine\Public\UnrealClient.h 63 87 TestThirdTwo
6 IntelliSense: identifier “FMeshBatchElement” is undefined ***\Unreal Engine\Launcher\Engine\Source\Runtime\ShaderCore\Public\VertexFactory.h 488 131 TestThirdTwo
7 IntelliSense: identifier “FOnSelectedLevelsChangedEvent” is undefined ***\Unreal Engine\Launcher\Engine\Source\Runtime\Engine\Classes\Engine\World.h 1929 2 TestThirdTwo
8 IntelliSense: identifier “UParticleModuleEventSendToGame” is undefined ***\Unreal Engine\Launcher\Engine\Source\Runtime\Engine\Classes\Particles\ParticleSystemComponent.h 886 68 TestThirdTwo
9 IntelliSense: identifier “UParticleModuleEventSendToGame” is undefined ***\Unreal Engine\Launcher\Engine\Source\Runtime\Engine\Classes\Particles\ParticleSystemComponent.h 899 68 TestThirdTwo
10 IntelliSense: identifier “UParticleModuleEventSendToGame” is undefined ***\Unreal Engine\Launcher\Engine\Source\Runtime\Engine\Classes\Particles\ParticleSystemComponent.h 917 69 TestThirdTwo
11 IntelliSense: identifier “UParticleModuleEventSendToGame” is undefined ***\Unreal Engine\Launcher\Engine\Source\Runtime\Engine\Classes\Particles\ParticleSystemComponent.h 929 42 TestThirdTwo

Seems like you didn’t declare your baseCollisionComponent variable in your pickup header file.