Lua Error

Dear All,

I am trying to output a numeric value using in a 4digit hexadecimal format in the following way:
" io.write(string.format("%04x", printchars)) "

I am getting an error as follows:

./pulse_parser.lua 2012年08月16日
/usr/bin/lua: ./pulse_parser.lua:16: bad argument #2 to 'format' (integer expected, got number)
stack traceback:
[C]: in function 'format'
./pulse_parser.lua:16: in function 'printwc'
./pulse_parser.lua:32: in function 'wc'
./pulse_parser.lua:45: in main chunk
[C]: ?

Can you please help me in finding a workaround with this?

I am running Lua on an OpenWRT device and Lua version is "Lua 5.1.4 Copyright (C) 1994-2008 Lua.org, PUC-Rio (double int32)"

I would like also to point out that everything works fine on my Ubuntu machine running "Lua 5.0.3 Copyright (C) 1994-2006 Tecgraf, PUC-Rio"

Thank you in anticipation,

Best Regards,

Edward Scerri