Problem with sending a message to BetaBrite via PC

My BetaBrite (213c-1) is connected to a lottery machine and I try to send messages to it using a software that I installed in the machine,
so my messages are being built not using the remote control but through my s/w (the language is C). When I build my message I must append to it some characters that identify the message (color, speed etc). for example: "C..E..B0' Hello world .n Bill Gates ..D0..." In this example the " Hello world" runs from left to right and then "Bill Gates" appears in color, but before "Bill Gates" the sign '?' appears with no reason. Does anyone know how to avoid this '?'. Do you have any article that can help me using those characters? (I got " http://www.teksolutionsllc.com/download/alphaprotodoc.pdf " - page 89, but it is not precisely working with '213c-1').
Yair
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