Variable replication problem

Hi, why when I replicate the variables on the Header files with the UPROPERTY(Replicated) macro, the compiler gives to me “unresolved external symbol”, and with UFUNCTION(Reliable, Server, WithValidation) that already exists, while it’s nowhere in the .cpp file?

http://puu.sh/d2tEB/bc340e2b51.png

http://puu.sh/d2tHo/b53564d7bd.png

I was wrong to write. The problem is with UPROEPRTY(Replicated), but it gives error with this UFUNCTION too.

http://puu.sh/d2tEB/bc340e2b51.png

http://puu.sh/d2tHo/b53564d7bd.png

Solved. I had to make

bool AUACharacter::ServerLookUpYaw_Validate()
{
	return true;
}

and

void AUACharacter::ServerLookUpYaw_Implementation()
{

}

and for the Variables:

#include "UnrealNetwork.h"
void AUACharacter::GetLifetimeReplicatedProps(TArray<FLifetimeProperty> & OutLifetimeProps) const
{
	Super::GetLifetimeReplicatedProps(OutLifetimeProps);

	DOREPLIFETIME(AUACharacter, Pitch);
	DOREPLIFETIME(AUACharacter, Yaw);
}