format PE GUI 4.0
include '%fasminc%\win32a.inc'

entry start

section '.data' data readable writeable
        FirstEditId     =   256
        SecondEditId    =   257
        ResultEditId    =   258
        ButtonId        =   259
        FirstUpDownId   =   260
        AddRadioId      =   261
        SubRadioId      =   262
        GroupBoxId      =   263
        FirstUpDownId   =   264
        SecondUpDownId  =   265
        First           dd 0
        Second          dd 0
        Result          dd 0
        wndMsg          MSG
        StaticCls       db 'STATIC', 0
        ButtonCls       db 'BUTTON', 0
        UpDownCls       db 'UPDOWN_CLASS', 0
        EditCls         db 'EDIT', 0
        Static1Text     db '0', 0
        Button1Text     db 'Push Me', 0
        UpDown1Text     db 'Spin1', 0
        UpDown2Text     db 'Spin2', 0
        AddText         db 'Add', 0
        SubText         db 'Sub', 0
        CalculateText   db 'Calculate', 0
        wndClsName      db 'TestCls', 0
        WindowHandle    dd ?
        InstanceHandle  dd ?
        MainWinText     db 'UPDOWN_CLASS Test', 0
        wc              WNDCLASS CS_HREDRAW+CS_VREDRAW+CS_DBLCLKS,DialogProc,0,0,NULL,NULL,NULL,COLOR_BTNFACE+1,NULL,wndClsName

section '.code' code readable executable
start:
        invoke  GetModuleHandle,NULL
                mov     [InstanceHandle],eax
                invoke  InitCommonControls
        invoke  RegisterClass,wc
        invoke  CreateWindowEx, 0,wndClsName,MainWinText,WS_MINIMIZEBOX+WS_VISIBLE+WS_MAXIMIZEBOX+WS_CAPTION+WS_BORDER+WS_SYSMENU,100, 100, 140, 200,NULL,NULL,[InstanceHandle],0
        mov     [WindowHandle], eax

wndMsgStart:
        invoke  GetMessage,wndMsg,NULL,0,0
                or   eax,eax
                je   wndMsgEnd
        invoke  TranslateMessage,wndMsg
        invoke  DispatchMessage,wndMsg
                jmp  wndMsgStart
wndMsgEnd:
        invoke  ExitProcess,0

proc DialogProc, hwndDlg, msg, wParam, lParam
                push ebx esi edi
                cmp     [msg], WM_CREATE
                je      .wmCREATE
                cmp     [msg], WM_COMMAND
                je      .wmCOMMAND
                cmp     [msg], WM_CLOSE
                je      .wmCLOSE
                cmp     [msg],WM_DESTROY
                je      .wmDESTROY

        .wmDEFAULT:
                invoke  DefWindowProc,[hwndDlg],[msg],[wParam],[lParam]
                jmp  .wmBYE

        .wmCREATE:
                invoke  CreateWindowEx, WS_EX_CLIENTEDGE,EditCls,NULL,WS_CHILD+WS_VISIBLE+ES_NUMBER+WS_TABSTOP+WS_GROUP,5, 5, 120, 20,[hwndDlg],FirstEditId,[InstanceHandle],0
                ;UPDOWN control below should be automatically 'buddied' to above edit control with UDS_AUTOBUDDY
                invoke  CreateWindowEx, 0,UpDownCls,UpDown1Text,UDS_AUTOBUDDY+UDS_ALIGNRIGHT+UDS_SETBUDDYINT+WS_CHILD+WS_VISIBLE+UDS_ARROWKEYS,105, 5, 20, 20,[hwndDlg],FirstUpDownId,[InstanceHandle],0
                invoke  SendDlgItemMessage, [hwndDlg], FirstUpDownId, UDM_SETRANGE, 0, 0064FF9Ch ;set range from -100 to 100

                invoke  CreateWindowEx, WS_EX_CLIENTEDGE,EditCls,NULL,WS_CHILD+WS_VISIBLE+ES_NUMBER+WS_TABSTOP,5, 35, 120, 20,[hwndDlg],SecondEditId,[InstanceHandle],0
                ;UPDOWN control below should be automatically 'buddied' to above edit control with UDS_AUTOBUDDY
                invoke  CreateWindowEx, 0,UpDownCls,UpDown2Text,UDS_AUTOBUDDY+UDS_ALIGNRIGHT+UDS_SETBUDDYINT+WS_CHILD+WS_VISIBLE+UDS_ARROWKEYS,105, 35, 20, 20,[hwndDlg],SecondUpDownId,[InstanceHandle],0
                invoke  SendDlgItemMessage, [hwndDlg], SecondUpDownId, UDM_SETRANGE, 0, 0064FF9Ch ;set range from -100 to 100

                invoke  CreateWindowEx, WS_EX_CLIENTEDGE,EditCls,NULL,WS_CHILD+WS_VISIBLE+ES_NUMBER+ES_READONLY,5, 65, 120, 20,[hwndDlg],ResultEditId,[InstanceHandle],0
                invoke  CreateWindowEx, 0,ButtonCls,AddText,WS_CHILD+WS_VISIBLE+WS_TABSTOP+BS_AUTORADIOBUTTON,10, 105, 50, 14,[hwndDlg],AddRadioId,[InstanceHandle],0
                invoke  CreateWindowEx, 0,ButtonCls,SubText,WS_CHILD+WS_VISIBLE+WS_TABSTOP+BS_AUTORADIOBUTTON,65, 105, 50, 14,[hwndDlg],SubRadioId,[InstanceHandle],0
                invoke  CreateWindowEx, 0,ButtonCls,CalculateText,WS_CHILD+WS_VISIBLE+WS_TABSTOP,5, 130, 120, 30,[hwndDlg],ButtonId,[InstanceHandle],0
                invoke  CreateWindowEx, 0,ButtonCls,NULL,WS_CHILD+WS_VISIBLE+BS_GROUPBOX,5, 85, 120, 40,[hwndDlg],GroupBoxId,[InstanceHandle],0
                invoke  CheckDlgButton, [hwndDlg], AddRadioId, BST_CHECKED
                jmp     .wmBYE

        .wmCOMMAND:
                cmp     [wParam], BN_CLICKED shl 16 + ButtonId
                je      .wmCOMMAND_ButtonID
                jmp     .wmBYE

            .wmCOMMAND_ButtonID:
                invoke  GetDlgItemInt, [hwndDlg], FirstEditId, 0, FALSE
                mov     [First], eax
                invoke  GetDlgItemInt, [hwndDlg], SecondEditId, 0, FALSE
                mov     [Second], eax
                invoke  IsDlgButtonChecked, [hwndDlg], AddRadioId
                cmp     eax, BST_CHECKED
                jne     .DoSubtract
            .DoAdd:
                mov     eax, [First]
                add     eax, [Second]
                jmp     @f
            .DoSubtract:
                mov     eax, [First]
                sub     eax, [Second]
            @@:
                mov     [Result], eax
                invoke  SetDlgItemInt, [hwndDlg], ResultEditId, [Result], TRUE
                jmp     .wmBYE

            .wmCLOSE:
                invoke  DestroyWindow,[hwndDlg]
                jmp     .wmBYE

            .wmDESTROY:
                invoke  PostQuitMessage,0

            .wmBYE:
                pop  edi esi ebx
                ret
endp

section '.idata' import data readable writeable
library kernel32,'KERNEL32.DLL',\
        user32,  'USER32.DLL',\
        gdi32,   'GDI32.DLL',\
        comdlg32,'COMDLG32.DLL',\
        advapi32,'ADVAPI32.DLL',\
        comctl32,'COMCTL32.DLL'

include '%fasminc%\apia\Kernel32.inc'
include '%fasminc%\apia\User32.inc'
include '%fasminc%\apia\Gdi32.inc'
include '%fasminc%\apia\Comdlg32.inc'
include '%fasminc%\apia\Advapi32.inc'
include '%fasminc%\apia\Comctl32.inc'    

You are not using the correct classname for the spin-control. It is actually
"msctls_updown32". The info in the api docs is wrong. Iczelion's tutorial on common controls has a correct list.

CreateWindow(UPDOWN_CLASS,
                   "Spin1",
                   UDS_AUTOBUDDY | UDS_ALIGNRIGHT |
                   UDS_SETBUDDYINT | WS_CHILD | WS_VISIBLE |
                   UDS_ARROWKEYS,
                   105, 5, 20, 20,
                   hwndDlg,
                   (HMENU )FirstUpDownId,
                   InstanceHandle,
                   0);
No surprise here. UPDOWN_CLASS is the name for an predefined wnd-class for updown controls.    

A tip for finding errors.

If you run GetLastError after CreateWindowEx in this case it returns 57f which in decimal is 1407. Looking up the system error codes we find:

ERROR_CANNOT_FIND_WND_CLASS
1407

 

CommCtrl.h: 

//====== UPDOWN CONTROL =======================================================

#ifndef NOUPDOWN

#ifdef _WIN32

#define UPDOWN_CLASSA           "msctls_updown32"
#define UPDOWN_CLASSW           L"msctls_updown32"

#ifdef UNICODE
#define  UPDOWN_CLASS           UPDOWN_CLASSW
#else
#define  UPDOWN_CLASS           UPDOWN_CLASSA
#endif

#else
#define UPDOWN_CLASS            "msctls_updown"
#endif