That's not what i suggested you do. Read Post #5 again and the other linked [Only registered and activated users can see links. ] carefully. You need to modify the current US/EU firmware to take a different TTS voice or you will get "Incompatiable Audio" message if that voice file is not supported in the current firmware. The only Thai voice presently supported is the non-TTS Thai__ (006-D0864-00) which is what i guess you've been using. Assuming you want a Thai TTS voice, what you need to do is change an unused voice such as Eesti (Estonian) to Narisa TTS and then flash the modified RGN using Updater.exe or as BIN files in an SD flash kit:

[Only registered and activated users can see links. ]