Button not updating - c++

Question

I have an application, a game, that I've been working on and I stuck with a button not been (visually) updated.
The button is a pause button. When the app starts it is disabled (has WS_DISABLED style), but when the user starts a game, I simply remove that style responsable to disable it (WS_DISABLED).
The problem is: the button remains (visually) with the disabled style (when removing the style).
Or remains (visually) with the enable style (when adding the style).
However, the button is correctly updated when I click in it. I assume that this is a repaint/update issue.
I tried to repaint the window (no sucess):
RedrawWindow(hWnd,NULL,NULL,RDW_ALLCHILDREN | RDW_UPDATENOW);
Here is the code fragment located in WinProc function:
switch (message) {
case WM_CREATE:
CreateControls(hWnd);
break;
case WM_COMMAND:
{
switch (HIWORD(wParam)) {
case BN_CLICKED:
switch (LOWORD(wParam)) {
case 3:
{
char text[50];
GetDlgItemTextA(hWnd, 3, text, 50);
HWND pauseB = GetDlgItem(hWnd, 4);
LONG style = GetWindowLong(pauseB, GWL_STYLE);
if (strncmp(text, "Start", strlen(text)) == 0) {
SetDlgItemTextA(hWnd, 3, "Stop");
SetWindowLong(pauseB, GWL_STYLE, style & ~WS_DISABLED);
std::thread bt(RunGame, hWnd);
bt.detach();
} else {
SetDlgItemTextA(hWnd, 3, "Start");
SetWindowLong(pauseB,GWL_STYLE,style | WS_DISABLED);
}
RedrawWindow(hWnd,NULL,NULL,RDW_ALLCHILDREN | RDW_UPDATENOW);
//SendMessage(hWnd, WM_PAINT, NULL, NULL);
}
default:
break;
}
break;
default:
break;
}
}
break;
// other cases...
}
I may confess that I don't know much about c++. So sorry for my mistakes.