lua how require works

I'm using a graphics library that lets you program in Lua. I have a need for the A* pathfinding library so I found one online. It's just 1 lua file that does the pathfinding and 1 example file. In the example file it uses the object like:

-- Loading the library
local Astar = require 'Astar'
Astar(map,1) -- Inits the library, sets the OBST_VALUE to 1

I run the script and everything works. So now I add the Astar.lua file to the path location where my graphics engine is running and do the same thing and I get the error on the Astar(map, 1) line:

"attempt to call local 'AStar' (a number value)

Any ideas why I would be getting that error when I'm doing the same thing as the example that comes with this AStar lib?

Here is a little of the AStar file

-- The Astar class
local Astar = {}
setmetatable(Astar, {__call = function(self,...) return self:init(...) end})
Astar.__index = Astar

-- Loads the map, sets the unwalkable value, inits pathfinding
function Astar:init(map,obstvalue)
    self.map = map
        self.OBST_VALUE = obstvalue or 1
    self.cList = {}
    self.oList = {}
    self.initialNode = false
    self.finalNode = false
    self.currentNode = false
    self.path = {}
    self.mapSizeX = #self.map[1]
    self.mapSizeY = #self.map
end

So note that when I run this from my graphics engine it's returning 1, but when run from the example that it came with it's returning a table, which is what it should be returning. So not sure why it would only be returning 1.