I tried a programme called subtitle droid and it works!
Last edited by freelance81 : 05-10-2013 at 22:27

Have you tried mkvmerge GUI? You just drag the movie into the "input" box. Then the subtitle file. Then "mux" it. You then should be able to enable subtitles in the MX player. I have to add that you do that on your PC before you copy it to your tablet.

http://www.videohelp.com/tools/MKVtoolnix