lua module is not loading libraries

Background Information:

I'm just new to lua and I'm trying to understand how modules work. But I'm trying to load a pre-existing module into a new script and run this script from the command line.

Code:

I have a file called main.lua module that looks something like this:

module (..., package.seeall)
-- Load libraries
require("luasql.postgres")
require("luasql.sqlite3")

local connect_to_db = function()
   if not global_con then
      env = assert (luasql.postgres())
      global_con = assert (env:connect(databasename, databaseUser, databasepassword, databaseserver))   
      return true
   else
      return false 
   end
end

update_widget = function (parm1, parm2, parm3)
  local connected = connect_to_db()         
  if connected then
     -- do something else
     return true
  end
end -- end function.

I'm now trying to create a test script for this module. I have the following logic in a separate lua file:

package.path = '/usr/share/myapp/main.lua;'
local my_object = require("main")

print my_object.update_widget

Problem:

I'm getting the following error when I try to run my test script:

attempt to call field 'postgres' (a table value)

The line it's failing on is in the connect_to_db() method where I try to create an environment variable:

env = assert (luasql.postgres())

What I've Tried so far:

1. I've modified the package.path in my test script to match what is being used by main.lua. I did so by executing main.lua the "regular" way - driven by a web app - and dumping out the contents of package.path to a log file. I've copied the path from the log file and used it as the package.path value in my test script... of course, I had to modify it by adding an additional entry - a path leading to main.lua.
   But other than that, the package paths are the same.

2. I've added print statements inside main.lua to prove that it is getting into the update_widget method... and that it's just failing trying to create the postgres.

3. I've added the luasql.postgres library in the test script to see if that would help... like so:

   package.path = '/var/x/appname/main.lua;'
   
   local pgdb = require("luasql.posgres")
   
   print(pgdb)
   myenv = assert(lua.postgres()) -- fails
   

The test script also dies trying to create this object... I'm going to keep hunting around. It must be a problem with the paths... but I can't see the difference between the path thats created when loaded by the web app, vs. what I have in the test script. I'm going to use a DIFF tool to compare for now.

Any suggestions would be appreciated.

Thanks.

EDIT 1

I definitely think it's the path, although I can't see just yet what's wrong with here. I created yet another test script (let's call it test3).. but this time, I didn't explicitly set the path by assigning values to package.path. I just tried to include the luasql.postgres pacakge and use it the way the original test script does... and it works! So here's code that works:

luasql = require "luasql.postgres"
local myenv = assert (luasql.postgres())
print(myenv)

But this fails:

package.path = package.path .. ';/usr/share/myapp/main.lua'

luasql = require "luasql.postgres"
myenv = assert (luasql.postgres())
print(myenv)

Also to greatwolf's point, I tried from interactive mode in lua... and my code works just fine.

Lua 5.1.5  Copyright (C) 1994-2012 Lua.org, PUC-Rio
> pgdb = require("luasql.postgres")
> print(pgdb)
table: 0x176cb228
> myenv=assert(luasql.postgres())
> print(myenv)
PostgreSQL environment (0x176c9d5c)
> 

So... here's the package.path variable from interactive mode:

> print(package.path)
./?.lua;/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua;/usr/local/lib/lua/5.1/?.lua;/usr/local/lib/lua/5.1/?/init.lua;/usr/share/lua/5.1/?.lua;/usr/share/lua/5.1/?/init.lua
> 

And here's the path from my original test script where it fails.

/usr/share/myapp/main.lua;./?.lua;/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua;/usr/local/lib/lua/5.1/?.lua;/usr/local/lib/lua/5.1/?/init.lua;/usr/share/lua/5.1/?.lua;/usr/share/lua/5.1/?/init.lua