Kinda stupid - I actually forgot how to handle buttons

Code:
HWND hBtn;

hBtn = CreateWindowEx(
                0,                                      //more or 'extended' styles
                TEXT("BUTTON"),                         //'class' of control to create
                TEXT("Submit"),            //the control caption
                WS_CHILD|WS_VISIBLE|BS_DEFPUSHBUTTON,   //control style: how it looks
                20,                                     //control position: left
                440,                                     //control position: top
                75,                                    //control width
                25,                                     //control height
                hGroupWarr,                                   //parent window handle
                (HMENU)BTN_SUBMIT,                                   //control's ID
                hThisInstance,                                //application instance
                NULL
        );   
        SendMessage(hBtn,WM_SETFONT,(WPARAM)GetStockObject(DEFAULT_GUI_FONT),0);
In WM_COMMAND:

Code:
if (HIWORD(wParam) == BN_CLICKED) {
        MessageBox(hwnd, "lol", "lol", MB_OK);
}
BTN_SUBMIT defined as:

Code:
#define BTN_SUBMIT 100
The messagebox doesnt pop up?