Invalid .vtt file notification

I am getting an “Invalid .vtt” notifcation when I try to add English-language subtitles for a film. I have converted it from .srt using two different platforms and get the same response. I have read through the file and can find no obvious problems. Please help.

Below is a sample of the .vtt as I cannot figure out a way to attache the file.

WEBVTT

1
00:00:00.691 → 00:00:08.490
Shkurnik
(a person seeking personal advantage)

2
00:00:09.615 → 00:00:13.715
A satirical novel
in 7 parts

3
00:00:15.991 → 00:00:19.142
Directed by: Mykola Shpikovsky

4
00:00:19.731 → 00:00:22.584
Director of photography :
Oleksandr Pankratiev

5
00:00:23.040 → 00:00:25.949
Assistant:
L. Lyashenko

6
00:00:26.423 → 00:00:30.015
Artist:
Solomon Zaritsky

It looks like the character is causing this to be invalid.

Replacing it with --> allows this sample to pass the validator.