Attempt to train the neural network

[MarekNovak1]

Hello, I would like to try your neural network for Slovak language. I would like to put a corpus of Slovak data into it and try to train it to generate backchannel in Slovak.
I tried training the neural network with the command I found in the readme, but it gave me errors that some wav files were missing. I have inserted only the wav files that were included in the demo into the conversations files (conversations.all, conversations.valid, conversations.eval, conversations.train). It ran for a while and then it returned this error (see image).
Could you give me any advice on how to proceed with this?
Thank you.