Assuming you can even get the LVTTS.LLB to work, you simply need to connect the OCR output to the TTS input.
Try this instead.
Download FESTIVAL from http://homepages.inf.ed.ac.uk/jyamagis/release/FreeVoices-WindowsBinary.zip
Put the extracted folder at C:\Festival This is important, or Festival will not work.
Use the system Exec.vi
Wire [c:\festival\festival.exe --tts] to the command line
and wire [This is a test], or whatever you want to say to the standard input.
There are other commands that Festival supports for changing the voice, and other things.
