Why does Windows SendMessage() always return ZERO, even the message delivery is success? Is there anyway to check the message delivery failure with SendMessage() ?
EDIT
Forgot to mention that I'm using SendMessage() inside a c++ DLL
LRESULT result = ::SendMessage(hwndOtherWindow,WM_COPYDATA, NULL/*(WPARAM)this->GetSafeHwnd()*/,(LPARAM)&structCDS);
"result" is always zero :(, but message delivers to other window successfully
EDIT
BOOL CDlg::OnCopyData(CWnd* pWnd, COPYDATASTRUCT* pCopyDataStruct)
{
return /*CDialog::OnCopyData(pWnd, pCopyDataStruct)*/ true; //true is the trick
}