Real player & now Realplayer 20/20 does not recognize about 70% of mkv files. You can play them via Real player, but if you try to burn them to DVD you instantly get a message 'This software in incompatible with Real Player'. If you try to convert them to any other format (mp4, wmv, Real media HD), you get a message | 'Status Failed - There were Errors' | within 2 seconds of starting the conversion.
The other 30% of mkv files work and burn as normal. Must be slightly different software.
However, If you use another converter, for example VLC media players converter, you can convert the mkv files (that Real Player does not like) to mp4 without issue, and then put the new mp4 copies back on Real Player where they will burn without issue!
Please update the Real Player software to recognize all mkv files. Thanks.