Linking error

[sourcecode]
#include<d3dx9.h>             

#define D3DFVF_D3DVertex (D3DFVF_XYZ|D3DFVF_DIFFUSE)

// Here are our Direct3D objects.  The first is used to get access to Direct3D
// and the second will be used to render to the screen.
LPDIRECT3D9 Direct3D_Object = NULL;
LPDIRECT3DDEVICE9 D3D_Device = NULL;



// This is the Windows procedure (WndProc).  This handles messages that the
// windows operating sends to your application.
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch(message)
       {
		   case WM_KEYUP:
            // If the user presses the escape key then exit the application.
            if(wParam == VK_ESCAPE)
               PostQuitMessage(0);
            break;

         case WM_DESTROY:
         case WM_CLOSE:
            PostQuitMessage(0);
            break;

            default:
               break;
       }

    return DefWindowProc( hwnd, message, wParam, lParam );
}


// This is the WinMain class.
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
   HWND hwnd;                 // Handle to the window.
   WNDCLASSEX windowClass;    // Window class object.
   bool done = false;         // Used to test if the app is running or not.

   // This is the Window class.
   windowClass.cbSize = sizeof(WNDCLASSEX);           // size of the WNDCLASSEX structure.
   windowClass.style = CS_HREDRAW | CS_VREDRAW;       // style of the window.
   windowClass.lpfnWndProc = WndProc;                 // Address to the windows procedure.
   windowClass.cbClsExtra = 0;                        // Extra class information.
   windowClass.cbWndExtra = 0;                        // Extra window information.
   windowClass.hInstance = hInstance;                 // Handle of application Instance.
   windowClass.hIcon = LoadIcon(NULL, IDI_APPLICATION);// Window Icon.
   windowClass.hCursor = LoadCursor(NULL, IDC_ARROW); // Load mouse cursor.
   windowClass.hbrBackground = NULL;                  // Background color.
   windowClass.lpszMenuName = NULL;                   // Menu.
   windowClass.lpszClassName = "UGPClass";            // Name of the window class.
   windowClass.hIconSm = LoadIcon(NULL, IDI_APPLICATION);// Minimized window icon.

   // You must register you class with Windows.
   if(!RegisterClassEx(&windowClass))
      return 0;

   // Create the window.
   hwnd = CreateWindowEx(NULL,      // The extended window style.
                         "UGPClass",// Window class.
                         "Direct3D Tutorial by The Programming Ace",// Window name.
                          WS_OVERLAPPEDWINDOW | WS_VISIBLE |         // Window style.
                          WS_SYSMENU |WS_CLIPCHILDREN |              // Window style.
                          WS_CLIPSIBLINGS,                           // Window style.
                          100, 100,                                  // X, Y coords.
                          400, 400,                                  // Window size.
                          NULL,                                      // Handle to parent window.
                          NULL,                                      // Menu.
                          hInstance,                                 // Handle to app instance.
                          NULL);                                     // Pointer to window.


   // If there was an error with creating the window, then close the program.
   if(!hwnd)
      return 0;


   ShowWindow(hwnd, SW_SHOW);    // Show the window.
   UpdateWindow(hwnd);           // Update its display.


   done = false;  // false = run program, true means stop.
   return 0;
}
[/sourcecode]