Costom Func

[#Paper]

What's wrong in this func?

function savePlayerData (player,datatype,newvalue) 
  local playerIP = getPlayerSerial(source) 
  if (playerIP) then 
    local root = xmlLoadFile ("users.xml") 
    if (root) then 
      local usersNode = xmlFindChild (root,"user",0) 
      if (usersNode) then 
        local playerRootNode = xmlFindChild (usersNode,"SERIAL_" .. getPlayerSerial(player),0) 
        if not (playerRootNode == false) then 
          local newNodeValue = xmlNodeSetAttribute (playerRootNode,datatype,newvalue) 
          xmlSaveFile ("users.xml") 
          xmlUnloadFile ("users.xml") 
          return newNodeValue 
        else 
          local playerRootNode = xmlCreateChild (usersNode,"SERIAL_" .. getPlayerSerial(player)) 
          local newNodeValue = xmlNodeSetAttribute (playerRootNode,datatype,newvalue) 
          xmlSaveFile ("users.xml") 
          xmlUnloadFile ("users.xml") 
          return newNodeValue 
        end 
      end 
    end 
  end 
end 

[Aibo]

there's is a "player" here:

function savePlayerData (player,datatype,newvalue)

and "source" on the next line:

local playerIP = getPlayerSerial(source)

is source even passed to this function? otherwise i don't see what else is wrong.