var
    hSubKey   : HKEY;
    MyValType : DWORD;
    BufSize   : DWORD;
    Buf: Pointer;
.....
      if RegOpenKey(RootKey, SubKey,hSubKey) = ERROR_SUCCESS then
        try
          if RegQueryValueEx(hSubKey, ValueName, nil, @MyValType, nil, @BufSize) =ERROR_SUCCESS then
            begin
              GetMem(Buf, BufSize);
              try
                if  RegQueryValueEx(hSubKey, ValueName, nil, @MyValType, Buf, @BufSize) =ERROR_SUCCESS then
                  begin
                      end;
......