Some characters are not allowed by Lua

I'm having a really odd issue with a Lua implementation into my C++ project. For some reason, it doesn't allow scripts containing characters like #, :, % (and some more, less important) to be executed.

In the results...

I need to use for i = 1, table.getn(tbl) do instead of for i = 1, #tbl do.

I need to use string.gsub(str, [..]) instead of str:gsub([..]).

and so on... This is getting really annoying looking for a work-arounds.

My first thought was the encoding. I have tried with multiple common encodings though and none worked.

What might be the problem? I will appreciate every solution because I am out of ideas.

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Specifications:

Lua version:

#define LUA_VERSION "Lua 5.0.3"

C++ 11, FreeBSD 10