16 bit wav is probably the problem, that's what happened to me when I tried to make a Jinriki utau also.
So, Continuing off from the 16 bit wav thing... It needs to be mono audio, the audio rate needs to be 44,100 (I might be wrong if so, omg I'm so, so sorry).
When you are naming the audio file, you'll probably see a 32-bit Signed, WAV or 64-bit Signed WAV, you NEED to switch that to 16-bit Signed WAV, if done correctly you'll see it normally.
I hope this helps ^-^