Error   LNK2019 unresolved external symbol "public: void __thiscall dt::move(int)" (?move@dt@@QAEXH@Z) referenced in function _WinMain@16

#include <Windows.h>
#include "Graphics.h"
#include "ResourseDll.h"

int CALLBACK WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance, LPSTR lCmdLine, int nCmdShow)
{
    Graphics* core=0;
    core = new Graphics;
    if (!core)
    {
        return 0;
    }
    core->Initialize(hInstance);
    dt bx;
    bx.a = 4;
    bx.move(54);

    if (core)
    {
        delete core;
        core = 0;
    }
}

ResourseDll.h
#pragma once

class dt {
public:
    int a;
    __declspec(dllexport) void move(int b);
};

ResourseDll.cpp
#include "stdafx.h"
#include "ResourseDll.h"

void dt::move(int b)
{
    a++;
}