help with splitting strings

[Merick <Merick_TeVaran@...>]

I'm using this function from the lua users wiki:

function Split(str, delim, maxNb) -- from: 
http://lua-users.org/wiki/StringRecipes
   -- Eliminate bad cases...
   if string.find(str, delim) == nil then
       return { str }
   end
   if maxNb == nil or maxNb < 1 then
       maxNb = 0    -- No limit
   end
   local result = {}
   local pat = "(.-)" .. delim .. "()"
   local nb = 0
   local lastPos
   for part, pos in string.gfind(str, pat) do
       nb = nb + 1
       result[nb] = part
       lastPos = pos
       if nb == maxNb then break end
   end
   -- Handle the last field
   if nb ~= maxNb then
       result[nb + 1] = string.sub(str, lastPos)
   end
   return result
end

If I do this:

args = Split("byval filename as zstring ptr, byval force_channels as 
integer, byval reuse_texture_ID as uinteger, byval flags as uinteger", ",")

then it works as expected and splits the string at the commas and 
returns a table with the segments. However, if I try to do it again like 
this:

words = Split(args[1], " ")
or
words = Split(args[1], "%s")

then what I get is a table with each element set to nil