Serial Program Problem!

int WINAPI WinMain (HINSTANCE hThisInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR lpszArgument,
                     int nCmdShow)
{
    HWND hwnd;               /* This is the handle for our window */
    MSG messages;            /* Here messages to the application are saved */
    WNDCLASSEX wincl;        /* Data structure for the windowclass */

//    CREATES WINDOW!


    /* Run the message loop. It will run until GetMessage() returns 0 */
    while (GetMessage (&messages, NULL, 0, 0))
    {
        /* Translate virtual-key messages into character messages */
        TranslateMessage(&messages);
        /* Send message to WindowProcedure */
        DispatchMessage(&messages);
    }

    /
}



LRESULT CALLBACK WindowProcedure (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
//Caso o botao1 seja apertado;//
int     gwtstat = 0;
int I;
char *  t = &textSaved[0];
char pcCommPort[50] = "COM4";
char SuceText[] = {"Connected"};
char stopedcon[]= {"Connection Stoped"};
char ErrorText[] = {"Error Connecting"};
char ConnectionError[] = {"Port Not Connected"};
int x[300]={0},y[300]={0},z[300]={0},v[300]={0};
int vetor1[500],vetor2[500];

/*--- Estrutura para quando pintar a tela ---*/
PAINTSTRUCT ps;
HDC         hdc;
TEXTMETRIC  tm;     //Decide o tamanho das letras
TCHAR       teste[]={"Exame:"};
/*--------------SERIAL------------------*/
int tx;
DWORD num;
byte in[2]={0};
/*-------------------------------------------*/


    switch (message)                  /* handle the messages */
    {
    case WM_CREATE:

        AddMenus(hwnd);//Adiciona Menus a janela

        TextBox = CreateWindow("EDIT",
                              "",
                              WS_BORDER | WS_CHILD | WS_VISIBLE,
                              10, 40,400,20,
                              hwnd,NULL,NULL,NULL);

        CreateWindow("BUTTON",
                     "SAVE",
                     WS_VISIBLE | WS_CHILD | WS_BORDER,
                     420, 40, 70, 20,
                     hwnd, (HMENU) 1, NULL, NULL);

        CreateWindow("BUTTON",
                     "START",
                     WS_VISIBLE | WS_CHILD | WS_BORDER,
                     420, 80, 70, 20,
                     hwnd, (HMENU) 2, NULL, NULL);

        CreateWindow("BUTTON",
                     "STOP",
                     WS_VISIBLE | WS_CHILD | WS_BORDER,
                     300, 80, 70, 20,
                     hwnd, (HMENU) 6, NULL, NULL);
                break;


    case WM_PAINT:
                hdc = BeginPaint(hwnd,&ps);
                FillRect(hdc,&ps.rcPaint,(HBRUSH)(COLOR_WINDOW+1)); 
                Rectangle(hdc,10,110,500,300);
                for (I=0;I<50;I++){
                    SetPixel(hdc,I,I,RGB(255,0,0));
                }
                TextOut(hdc,1,1,teste,strlen(teste));    
                EndPaint(hwnd,&ps);
                break;

    case WM_TIMER:
                // To do: invalidar apenas uma pequena regiao
                tx = ReadFile(hCom,&in,1,&num,NULL);
                printf("%x\t",(in[0]));
                 hdc = GetDC(hwnd);
                       SetPixel(hdc,i,in[0],RGB(255,0,0));
                       ReleaseDC(hwnd,hdc);
                i++;




                //InvalidateRect (hwnd, NULL, FALSE) ;
               /* for(i=0;i<1000;i){
                       hdc = GetDC(hwnd);
                       SetPixel(hdc,i,in[i],RGB(255,0,0));
                       ReleaseDC(hwnd,hdc);*/
                //}


                break;
    case WM_COMMAND:
        switch (LOWORD(wParam)){
            case BUTTON1:
                gwtstat = GetWindowText(TextBox,t, 20);
                ::MessageBox(hwnd,textSaved,textSaved,MB_OK);
                fopen("info.txt","a+");
                fwrite(teste,1,sizeof(teste),fp);
                break;

            case BUTTON2:
                hCom = CreateFile( pcCommPort,
                                GENERIC_READ | GENERIC_WRITE,
                                0,    // must be opened with exclusive-access
                                NULL, // no security attributes
                                OPEN_EXISTING, // must use OPEN_EXISTING
                                0,    // not overlapped I/O
                                NULL  // hTemplate must be NULL for comm devices
                    );


                if (hCom == INVALID_HANDLE_VALUE)
                {
                    ::MessageBox(hwnd,ConnectionError,ConnectionError,MB_OK);
                   return (1);
                }


               fSuccess = GetCommState(hCom, &dcb);

               if (!fSuccess)
               {
                    return (2);
               }

                dcb.BaudRate = CBR_9600;     // set the baud rate
                dcb.ByteSize = 8;             // data size, xmit, and rcv
                dcb.Parity = ODDPARITY;        // no parity bit
                dcb.StopBits = ONESTOPBIT;    // one stop bit

                fSuccess = SetCommState(hCom, &dcb);

                if (!fSuccess)
                {
                ::MessageBox(hwnd,ConnectionError,ConnectionError,MB_OK);
                  return (3);
                }
                ::MessageBox(hwnd,SuceText,SuceText,MB_OK);

                SetTimer(hwnd,1,0x1,NULL);
                /*
                if (tx == TRUE) {
                    printf("%d",in[0]);
                }
                else{
                    ::MessageBox(hwnd,ConnectionError,ConnectionError,MB_OK);
                }*/

                break;
            case IDM_FILE_NEW:
                Beep(100, 100);
                break;
            case IDM_FILE_OPEN:
                Beep(50, 100);
                break;
            case IDM_FILE_QUIT:
                SendMessage(hwnd,WM_CLOSE,0,0);
                break;
            case STOP:
                KillTimer(hwnd,1);
                if (CloseHandle(hCom)==0){
                ::MessageBox(hwnd,ErrorText,NULL,MB_OK);
                }
                else{
                ::MessageBox(hwnd,stopedcon,stopedcon,MB_OK);
                }
                break;
        }

    /*case WM_DESTROY:
            PostQuitMessage (0);       //send a WM_QUIT to the message queue
            KillTimer (hwnd, 1) ;
            break;*/

            default:                      /* for messages that we don't deal with */
                return DefWindowProc (hwnd, message, wParam, lParam);
            }

    return 0;
}