Problem getting Caption of a window control using SendMessage & WM_GETTEXT

[C++ Programming]

Hi There.

I am trying to get a caption of a windows control using below code... But its fatching only a set of square boxes (Carriage return).

TCHAR buf[512];
::SendMessage(pWaitingProcessCompleteWnd6, WM_GETTEXT, 0 , (LPARAM)buf);

I have checked the address of pWaitingProcessCompleteWnd6 using spy++, its pointing to the right control.

Please help.

Thanks
PanB