clipboard could not work completely

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C++

Hey,guys.I'd tring to copy a string into clipboard.But my code just copy the first character.I don't know why?Hope you can help me.Thanks.Here's my code.

void CopyMacroToCB(HWND hwnd) {
	HGLOBAL hGlobal;
	TCHAR* pGlobalStr;
        SIZE_T cbStrBuf = 5000;
	hGlobal = GlobalAlloc( GHND | GMEM_SHARE,cbStrBuf );
	pGlobalStr = (TCHAR*)GlobalLock(hGlobal);
	wcscat_s( pGlobalStr,cbStrBuf/2,_T("copy to clipboard\r\n") );
	GlobalUnlock(hGlobal);
	OpenClipboard(hwnd);
	EmptyClipboard();
	SetClipboardData( CF_TEXT,hGlobal );
	CloseClipboard();
}