xmlSimple.lua:105: attempt to index global 'system' (a nil value)

[wcss2010]

$ lua52 test2.lua
c:\Program Files\LuaShell\lua52.exe: .\xmlSimple.lua:105: attempt to index global 'system' (a nil value)
stack traceback:
.\xmlSimple.lua:105: in function 'loadFile'
test2.lua:3: in main chunk
[C]: in ?

Code:
local xml = require("xmlSimple").newParser()
local xmlData= xml:loadFile("C:/luaStudy/t.xml")
print(#xmlData.test)