[string "function string.explode(s, pattern, plain)..."]:23: attempt to index local 'haystack' (a nil value)Problem solved.
Because I did not give any build option, the _ACTION variable was nil rather than “gmake” or “vs2008”.
And string.startwith (nil, “vs”) was having problem.
So I replaced: if string.startswith(_ACTION, “vs”) then by
if _ACTION ~= nil and string.startswith(_ACTION,“vs”) then