LuaXML使用Lua解析XML

我正在尝试使用[LuaXML]（http://viremo.eludi.net/LuaXML/）解析XML文件

function customURLtoSteam64(web, sid)
local xml = require("luaXml")
local xfile = xml.load("http://steamcommunity.com/id/GreenMarineValve?xml=1") --line189
local xscene = xfile:find("steamID64[1]")
return render_front(web, xscene)
end

但是我收到了以下错误：

.\index.lua:189: attempt to index local 'xml' (a boolean value)
stack traceback:
.\index.lua:189: in function <.\index.lua:186>
(tail call): ?
(tail call): ?.\index.lua:189: attempt to index local 'xml' (a boolean value)
stack traceback:
c:\Lua\LuaRocks/share/lua/5.1/coxpcall.lua:24: in function
(tail call): ?
(tail call): ?
c:\Lua\LuaRocks/share/lua/5.1/orbit.lua:540: in function
(tail call): ?
(tail call): ?

我不明白出了什么问题，怎么才能正确地做到这一点？