Control sequences to ZVT-Terminal

[dav <dav01it yahoo it>]

If I use the sintax:

write(zvt->vx->vt.keyfd, string, sizeof(string));

to send contro characters to the terminal nothing works.
The same sequence works with the command line:
echo -e "\033>"

(this sequences re-enables the numeric pad)
I think that since "zvt->vx->vt.keyfd" emulates a keystroke the terminal
ignores it as control sequence.

Suggestions?

Thanks.