🚀 go-pugleaf

Hi everyone,
Is it impossible to create a child window inside a dialog box ?
Well, I have created a dialog box through CreateDialog, and in
the WM_INITDIALOG message handler, I create a child window this
way :

hWndChart = CreateWindow("WndChart",
 "",
 WS_CHILD | WS_VISIBLE,
 100, 150,
 100, 30,
 hwnd,
 NULL,
 hInst,
 NULL);

where hwnd is the parameter passed to the dialog procedure, hInst
the gloval variable and "WndChart" a window class name registered
this way :

WNDCLASS wc;
wc.style = 0;
wc.lpfnWndProc = Chart_WndProc;  // The child window procedure
wc.cbClsExtra = 0;
wc.cbWndExtra = 0;
wc.hInstance = hInst;
wc.hCursor = LoadCursor(0, IDC_CROSS);
wc.hbrBackground = (HBRUSH) CreateSolidBrush (PALETTERGB(255,128,128));
wc.lpszMenuName = 0;
wc.lpszClassName = "WndChart";
wc.hIcon = NULL;
RegisterClass(&wc);

The function RegisterClass returns true so the registration process
is successful. Though, hWndChart (returned by CreateWindow) is NULL.
A call to GetLastError returns the error 87 : invalid parameter.
What did I do wrong ?

Thanks in advance,
Mark