You must use a voice from
IGo 8.3 or Primo having a file structure containing files like "command.csv" and "rules.txt" or "rules2.txt" If you try to use a very recent voice (TTS-Pro voice) able to work either with Loquendo, Nuance ... with a structure containing *.lua files, I think that it will not work.
You need probably to modifiy slightly the "info.ini" files inside de ZIP archive of the voice. There are just a few things to modify :
ttsvoice=1
tts_engine="svox" (I think that it must be loquendo inside the archive you will use. So modify this parameter)
tts_srate="11025" (this parameters is needed in order to have the proper natural tone of the voice. The value is probably 22050, to be modified)
tts_mode_mixed=0