My PhysicMaterial is null !?

for some strange resson my PhysicMaterial is null and i cant work with it!

This gets called everytime i call my moveFunction.

void AArcadeShooterCharacter::Footsteps()
	if (CanJump())
		if (footCounter < maxFootCounter)footCounter++; else
			footCounter = 0;
			FVector start = GetActorLocation();
			FVector end = FVector(start.X, start.Y, start.Z - 500);
			FCollisionQueryParams params(FName(TEXT("Footsteps")), false, this);
			FHitResult hit(ForceInit);

			if (RayCast(hit, params, 500, start, end))
				if (hit.PhysMaterial == NULL){ UE_LOG(LogTemp, Warning, TEXT("NULL")); }
					UE_LOG(LogTemp, Warning, TEXT("Valid"));
				if (materialType == MaterialType::Grass) UGameplayStatics::PlaySoundAtLocation(this, GrassSound, GetActorLocation());
				if (materialType == MaterialType::Wood) UGameplayStatics::PlaySoundAtLocation(this, WoodSound, GetActorLocation());
				if (materialType == MaterialType::Stone) UGameplayStatics::PlaySoundAtLocation(this, StoneSound, GetActorLocation());
				if (materialType == MaterialType::Water) UGameplayStatics::PlaySoundAtLocation(this, WaterSound, GetActorLocation());

Heres my SingleTrace

bool AArcadeShooterCharacter::RayCast(FHitResult RV_Hit, FCollisionQueryParams params, float d, FVector Start, FVector End)
	params.bReturnPhysicalMaterial = true;
	params.bTraceAsyncScene = true;
	params.bTraceComplex = true;
	bool DidTrace = GetWorld()->LineTraceSingle(RV_Hit,Start,End,ECC_Pawn,params);
	return DidTrace;

and if i want to use hit.PhysMaterial->SurfaceType; when i get “Pointer to incomplete class type is not allowed” ?
What am iam doing wrong ?
Iam new to UE4’s c++. So please excuse my bad code writing iam still learning.

If anyone finds this if your PhysMaterial is null don’t forget to put bReturnPhysicalMaterial to true and also try to set bTraceComplex to false or change the collision of your meshes to “Simple collisions as complex”