Unicode下RegQueryValueEx读取注册表值问题

HKEY   hkey;   
TCHAR   sz[256];   
DWORD   dwtype,   sl   =   256;   
 
RegOpenKeyEx(HKEY_CLASSES_ROOT,   
L"Word.Document.8\\shell\\Open\\command",   
NULL,   KEY_QUERY_VALUE ,   &hkey);   
RegQueryValueEx(hkey,   NULL,   NULL,   NULL,   (LPBYTE) sz,   &sl);   
RegCloseKey(hkey);