LNK2019 from class instancing

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C++

MFC

Simple class to hold and transfer data Doc->View.
Same class works fine in a test project but not where needed.
What am I missing? Any help appreciated.

LNK2019: unresolved external symbol "public: CSettings::CSettings(void)" referenced in function "protected: CFracturedDoc::CFracturedDoc(void)" (Abbreviated)

// Relevant CSettings.h File Code
#pragma once
#include "stdafx.h"
class CSettings
{
protected:
	double	m_nXMinimum;
	double	m_nXMaximum;
        // More simple variables
public:
	CSettings(void);
	~CSettings(void);
        // Gets and sets - No inline or virtual
};

// Relevant CSettings.cpp Code
#include "stdafx.h"
#include "CSettings.h"
CSettings::CSettings(void)
{
	this->m_nXMinimum = -2.0;
	this->m_nXMaximum = 2.0;
}
CSettings::~CSettings(void)
{
}

// Relevant CDoc.h Code
#pragma once
#include "CSettings.h"
class CFracturedDoc : public CDocument
{
protected:	// Create From Serialization Only
	CFracturedDoc();
	DECLARE_DYNCREATE(CFracturedDoc)
	CSettings* m_cSettings;  // No Grief here
public:
	CSettings* GetSettings(void);
};
// Relevant CDoc.cpp problem causing Code
#include "stdafx.h"
#include "CSettings.h"  // Error with or without include
#include "CFracturedDoc.h"
CFracturedDoc::CFracturedDoc()
{
	m_cSettings = new CSettings();  // Unresolved External Reference Grief
}