Estoy programando un guitar pro para el psp pero al iniciar me sale el Error: functions/misc.lua:61 attempt to call a table value.
Alguien me podria ayudar no se cual es el error, aqui esta el codigo.

function filesort(a, b)
if case_sorting == 0 then
a_name = string.lower(a.name)
b_name = string.lower(b.name)
else
a_name = a.name
b_name = b.name
end
if a.directory == b.directory then
return a_name < b_name
else
return a.directory
end
end

function mp_nextfile()
if menu_pointer + 1 <= num_files then
menu_pointer = menu_pointer + 1
else
menu_pointer = 3
start_pointer = 1
end
if (num_files > num_listings) and (menu_pointer == (start_pointer + num_listings)) then
start_pointer = start_pointer + 1
end
end

function mp_prevfile()
if (num_files > num_listings) and (menu_pointer == start_pointer) then
start_pointer = start_pointer - 1
end
if menu_pointer - 3 >= 1 then
menu_pointer = menu_pointer - 1
else
menu_pointer = num_files
if (num_files > num_listings) then
start_pointer = ((num_files - num_listings) + 1)
else
start_pointer = 1
end
end
end

function test_filetype(filename, extension)
-- if string.lower(string.sub(filename, -3)) == extension then return true end
local s,v,r = string.find(filename, "\.(%w*)$")
if string.lower(r) == extension then return true end
end

function update_files()

-- get current working directory
currentdir = System.currentDirectory("ms0:/GP4part")

-- get directory listing
files = System.listDirectory()
table.sort(files, filesort)
num_files = table.getn(files)

-- add actions
if file.directory then
directory = 1
else
directory = 0
end
file.action_cross = "file_action(\"" .. file.name .. "\", " .. directory .. ", \"execute\")"
file.action_square = "file_action(\"" .. file.name .. "\", " .. directory .. ", \"operation\")"
file.action_triangle = "file_select(\"" .. currentdir .. "\", \"" .. file.name .. "\", \"toggle\")"
end

-- update menu pointer
if menu_pointer >= (num_files + 1) then
menu_pointer = 3
end

-- reset start pointer
start_pointer = 1
menu_pointer = 3
-- reset selected files array
selected_files = {}

end

function is_dir(path, name)
local tmpfiles = System.listDirectory(path)
local found_needle = false
for k,v in pairs(tmpfiles) do
if v.name == name and v.directory then found_needle = true end
end
return found_needle
end

function get_filename(path_name)
return string.gsub(path_name, ".*/(.*[^\/])", "%1")
end

function get_filepath(path_name)
return string.gsub(path_name, "^(.+)/.*$", "%1")
end

function scan_dir(path, name)

-- set path
local path_name = remove_trailing_slash(path) .. "/" .. name

-- add dir to scan array
table.insert(scan_dirs, path_name)

-- get listing
tmplist = System.listDirectory(path_name)
table.sort(tmplist, filesort)
scan_tmp[path_name] = tmplist

-- loop listing
for k,v in pairs(scan_tmp[path_name]) do

-- skip ./..
if v.name ~= "." and v.name ~= ".." then

-- is dir
if is_dir(path_name, v.name) then

-- scan dir
scan_dir(path_name, v.name)

-- is file
else

-- add file to scan array
table.insert(scan_files, path_name .. "/" .. v.name)

end

end

end

end

no copien, si se preguntan porque estan en ingles los comentarios esque me gusta mas esa lengua.
Gracias