C++ DLL Class is crashing whilst creating a private member - c++

Question

I have a Problem and i am completely stuck.
First i show you the code:
Config for Building(NarviConfig.h):
#pragma once;
namespace Narvi
{
#ifdef NARVI_EXPORTS
#define _NarviExport __declspec(dllexport)
#else
#define _NarviExport __declspec(dllimport)
#endif
}
//-------------------------------------------
I have 2 Classes in a DLL like this:
The first One(NarviRoot.h):
Header:
#pragma once
#include "NarviConfig.h"
#include "NarviWindow.h"
namespace Narvi
{
class _NarviExport NarviRoot
{
public:
NarviRoot();
~NarviRoot();
public:
bool Init(void);
private:
NarviWindow* mWindow;
};
}
Source:-----------------------------
#include "NarviRoot.h"
namespace Narvi
{
NarviRoot::NarviRoot()
{
}
NarviRoot::~NarviRoot()
{
delete mWindow;
}
bool NarviRoot::Init(void)
{
mWindow = new NarviWindow();
return true;
}
}
//-----------------------------------------------------------------
The window(NarviWindow.h):
Header
#pragma once
#include "NarviConfig.h"
namespace Narvi
{
class _NarviExport NarviWindow
{
public:
NarviWindow();
~NarviWindow();
};
}
Source:--------------------------------
#include "NarviWindow.h"
namespace Narvi
{
NarviWindow::NarviWindow()
{
}
NarviWindow::~NarviWindow()
{
}
}
And this is my Testapp
mRoot = new Narvi::NarviRoot();
mRoot->Init();
It seems to work, but the program crashes when calling
mWindow = new NarviWindow();
Inside of
bool NarviRoot::Init(void)
{
mWindow = new NarviWindow();
return true;
}
and i can't figure out why.
If i write:
NarviWindow* mWindow = new NarviWindow();
it doesn't crash.
The constructor of NarviWindow is doing nothing, but it seems he can't access the private member mWindow.
I am pretty sure it is a simple error i made, but i can't see the wood for the trees.
Thank you! :)