FPS Camera Rotation Issue - Barrel Rolling

Hi, folk!

I’m trying to understand how UE works and, for that, I tried implementing some basic actors, such as a Pawn that has a FPS Camera to it. But I get a strange issue.
My camera goes nuts and starts to roll around, making the ground seem vertical. It’s barrel rolling. How do I stop that?

Here’s an image:

NOTE: I’m using a Pawn class as parent and using the old input version.

Here’s my Cpp code!

// PlayerCharacter.cpp

void APlayerCharacter::SetupPlayerInputComponent(UInputComponent* PlayerInputComponent)
{
	Super::SetupPlayerInputComponent(PlayerInputComponent);

	PlayerInputComponent->BindAxis(TEXT("MoveForward"), this, &APlayerCharacter::MoveForward);
	PlayerInputComponent->BindAxis(TEXT("MoveRight"), this, &APlayerCharacter::MoveRight);
	PlayerInputComponent->BindAxis(TEXT("RotateCamera"), this, &APlayerCharacter::RotateCamera);
	PlayerInputComponent->BindAxis(TEXT("LookUp"), this, &APlayerCharacter::LookUp);
}

void APlayerCharacter::RotateCamera(float AxisValue)
{
	FRotator NewRotation = Camera->GetRelativeRotation();
	NewRotation.Yaw += FMath::Clamp(AxisValue, -1.0f, 1.0f);
	Camera->SetRelativeRotation(NewRotation);
}

void APlayerCharacter::LookUp(float AxisValue)
{
	FRotator NewRotation = Camera->GetRelativeRotation();
	NewRotation.Pitch += FMath::Clamp(AxisValue, -1.0f, 1.0f);
	Camera->SetRelativeRotation(NewRotation);
}

What’s wrong with my code? How do I “clamp” my movement to the Y and X axis?

Thanks for the attention!