I really think you don't understand what getProperty does.
Just read http://www.leadwerks.com/werkspace/page/documentation/_/command-reference/system/systemgetproperty-r538
and you understand that it reads the parameter map when it is attached to the command-line.
The Editor does attach the map parameter with the currently in the editor loaded map so you can actually debug the loaded map when you press "Run". if the "map" parameter is not attached it loads the default map that is the second parameter in the getProperty method.
If you don't want to have the editor map loaded automatically you can just replace getProperty with your actual path.
so replace the line:
local mapfile = System:GetProperty("map","start.map")
with
local mapfile = "start.map"
also do not use absolute paths. That will surely give you issues sooner or later.
Also it seems you don't have Leadwerks installed in the default path. I am not sure how that affects everything but i think it was mentioned that it will make trouble at least when you try to develop for mobile.