GameplayAbilities and you

Hello,
I get this error:
2>D:\engine\Engine\Source\Runtime\CoreUObject\Public\UObject/Object.h(83): error C2027: use of undefined type ‘UAbilitySystemComponent’
2>D:\engine\Engine\Plugins\Runtime\GameplayAbilities\Source\GameplayAbilities\Public\AbilitySystemInterface.h(10): note: see declaration of ‘UAbilitySystemComponent’
2>D:\build\IS\Game\Source\InnerSanctum\ISPlayer.cpp(45): note: see reference to function template instantiation ‘TReturnType *UObject::CreateDefaultSubobject<UAbilitySystemComponent>(FName,bool)’ being compiled
2> with
2>
2> TReturnType=UAbilitySystemComponent
2> ]
2>D:\engine\Engine\Source\Runtime\CoreUObject\Public\UObject/Object.h(84): error C2440: ‘static_cast’: cannot convert from ‘UObject *’ to ‘UAbilitySystemComponent *’
2>D:\engine\Engine\Source\Runtime\CoreUObject\Public\UObject/Object.h(84): note: Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
when i add this:
AbilitySystem = CreateDefaultSubobject<UAbilitySystemComponent>(TEXT(“AbilitySystem”));
to my class

AbilitySystem is a class UAbilitySystemComponent*

my engine is currently 4.18

Does anyone know how to resolve this error?