I'm using an Octagon SX88 V2 with OpenVix 6.4. I am unable to get DVB subtitles. Text subtitles, when available, work just fine. But most channels offer DVB subtitles and I can't get these. The yellow subtitle button on the remote shows that there are subtitles but pressing "OK" does not cause subtitles to be dispalyed. I don't know whether this is a problem with the receiver or OpenVix or something I've set up incorrectly. I'd be grateful for guidance on how to fix this.